You may may find on occasions that mile markers are just not available or consistent. Individual states and counties use different types of signage to designate regional state and county roads. Be the first to know! Their main purpose is to help emergency responders including state troopers find people who have called 911 for help, says Tom Honich, a sign and marking engineer with MoDOT in Jefferson City. Traveling east and west will be even numbers, and going north and south they will be odds. WRONG! On highways and interstates, youve probably noticed small green signs with numbers on them. Also, it doesnt actually exist anymore. Your membership is the foundation of our sustainability and resilience. 2. a significant event in life, history, etc. He's on Instagram. Railroads have long had their mile markers, too. These routes are designated with the number of the main route and an even-numbered prefix. Mile markers usually change numbering at state borders. Fact. It means that a section of road is closed. Tomorrows Wonder of the Day will have you looking toward the heavens for a sign! The highway routes and interstate numbers can actually help you identify where you are in the U.S. You may not fully clear on the difference between a route and an interstate. Civil Rights/ADA | Derechos Civiles/ADA | Website Policies. North-south routes are assigned odd numbers, with the numbers growing larger from west to east; east-west routes are assigned even numbers, with the numbers growing larger from south to north. Notice that both Baltimore and Washington have their own spur I-395, but Baltimore doesnt have an I-495 because Washingtons Beltway enters Maryland. On east-west routes, the numbers begin on the western state border and increase as you travel east. Exit now and try our delicious food today! All of the images can be enlarged by clicking on them. However, without a device, could you understand it? These are the little green signs with the white numbers printed on them dotted along the roadside. Know your meals: If its breakfast, the suns in the East. It's a good thing to WONDER about, after all. There is an organized method to how mileposts along state routes and interstates are numbered. Likewise, what does this sign means? Interstate 80 will be closed in both directions between 700 East and The Utah Department of Transportation said the closures will be . This was the spot that inspired me to go ahead and compile the list. U.S. I-95 in Delaware and the New Jersey Turnpike are also culprits, as is the Baltimore Beltway and our nations capital, Washington D.C. Have you ever seen three seasons at once? What is the distance between mile markers? Hopkins Hill Rd. For example, when you see a sign that reads JRs Cheap Tobacco, Exit 59 that can clue you in to how far you have to go until you get there. Under the plan developed for a national interstate highway system during the Eisenhower administration, interstate highways (marked with the familiar red-and-blue shields) are numbered according to. The lowest numbers begin in the south and west, and get higher as you progressively move north and east. You also have the option to opt-out of these cookies. The system extends throughout the contiguous United States and has routes in Hawaii, Alaska, and Puerto Rico.. :) WOHOO! 14B. Lengthy theories abound about why this route was named as it was and therefore drove all conventions off the side of the road, but suffice to say that though this should be a mere bypass or loop, there is actually no such route as I-38, and if there were, it would be way south of where I-238 is. Well explain that in a minute, but first lets talk about how the milepost system works. Headed North on I-77? How to Market Your Business with Webinars? Advertisement cookies are used to provide visitors with relevant ads and marketing campaigns. Theres a logical system behind it all, and its easy to learn. A highway location marker is the modern-day equivalent of a milestone. Odds. < Less Than and > Greater Than. "Highway Numerology Muddled by Potholes in Logic." This 3,000 mile inland waterway is made up of natural inlets, saltwater rivers, bays, sounds, and man-made canals. (Highway 99 has since been supplanted by Interstate 5 and is no longer designated as a U.S. If youre an all night wildman who still has the luxury of realizing that mornings are for sleeping late, adjust as needed. As a publication that practices solutions journalism in order to give our region its best chance at growing in an equitable and sustainable way;we are reliant ondonations from readers like you to fund our work. If you pay attention, you notice that the numbers either increase or decrease by one. On east-west routes, the numbers begin on the western state border and increase as you travel east. Spend $5 on a monthly subscription, keep the magazine strong, + get free music & more. So, mile marker numbers always get larger as you travel east or north. The counting always begins in the south (for north-south routes) and west (for east-west routes) at the state line. The number of the highway youre on tells you where on the landscape of America you are. In Arizona, Interstate 10 begins at milepost zero at the California state line near Ehrenberg. Routes that are primary, run from single to three digits. On most interstates, mile marker numbers begin at the south state line on north-south routes and increase as you travel north. -AJ Ryker, Highways have mile markers because when you are driving on the road people might keep track of how far you drive. the Wonder of the Day via email or SMS. Interstate 90 crosses the USA from Seattle, Washington, to Boston, Massachusetts. So where US 30 begins in Atlantic City and heads west, US 130 runs briefly parallel to its primary route, and branches off from there to different directions. For example, this marker is Monterey County (MON). Each offers a variety of food choices, as well as fuel and other amenities. The short and inglorious I-99, shown in red. Say you have highway/route U.S. 20, there can be a a U.S. 20 Business route. Go for a drive on the highway with an adult. This sign warns you about hazards or possible hazards on or near the roadway. By adding 15+ miles I-275 is not of much use as a bypass and relieves a negligible amount of through traffic from I-71, I-74, or I-75. Ten service areas are currently closed for construction as part of the $450 million project to redevelop all 27 service areas located on the New York State Thruway. By clicking Accept All, you consent to the use of ALL the cookies. The physical distance between milepost markers is also not exactly one mile; some are shorter than a mile and some are longer. It may read I-47 Franklin go straight and 24 East Marion to the left 1 Mile. Public domain image. 2/East Greenwich/West Warwick. How are mile markers used in the United States? Interstate Routes, Mile Markers & Exit Numbering, highway signs, how do highway numbers work, how do interstate numbers work, how do mile markers work, how the interstate works, how the interstate works in the united states, how to exit numbers work, interstate signs, what is a business loop, what is a business route, what is the difference between a highway and an interstate. These "mile markers" show the number of miles from where the Interstate route entered the state in which you are traveling. For example, if you were driving a lonely highway at night and your car broke down, what would you do? There are two types of highways and interstates, primary and spurs, although interstate spurs are commonly called bypasses. Other times, when we travel far, we travel by plane or train. He has a degree in urban planning from the University of Coloradoand lives in Trinidad, DC. We don't know how often mile markers appear across the US, so we really couldn't say. Do you know how the Interstate works in the United States? Left, 1.1 miles. Play roadway math! So, mile marker numbers always get larger as you travel east or north. Billboards rarely provide any information that any of the above methods do, but when youre in Apache Country, Arizona and no government official has bothered to update the road signs since CHIPS got canceled, sometimes advertising can provide as many clues as Sherlock Holmes would ever need. US-6 W; W 159th St. Markham, Illinois. Meaning: Slow down as you approach the intersection. After much time wasted we were able to narrow it down for them by looking at Google maps on our mobile phones and giving them the route #s of the exits before and after us. Vehicles are not supposed to drive past the sign. See you soon! The interstate travels through the Deck Park Tunnelin the heart of Phoenix at milepost 145 and continues on to Tucson, where the milepost number hits 255. Mile after mile passes by on the lonesome highway. So, mile marker numbers always get larger as you travel east or north. Mileage is the distance along the road from a fixed commencement point. are spurs of US 1, US 101 is all on its own. TO EAST Market Street: 19B: TO WEST Market Street: 21: EAST Arsenal Road: Lancaster Harley Davidson Plant and Museum: 21A: EAST Arsenal Road: Lancaster Harley Davidson Plant and Museum: 21B: Those mile markers help us know where we are on the map. Also, if you were on I-10 intersecting with I-5, that would put you in Los Angeles California. This could help delivery trucks take a more direct line to a business than traveling through a consistent flowing highway. Wonder What's Next? Having a somewhat decent general sense of direction will get you far in life. 3 Why are there so many mile markers in Missouri? But did you ever stop to think how you'd tell them where you are? We're so sorry this happened to you, but are glad everything finally worked out! If you understand grids the better, but even if you dont, the above can tell you what area of America you are in by the numbers. This cookie is set by GDPR Cookie Consent plugin. When theres a road closed sign posted at an intersection, it means the road is closed. Lets say you heading west and you know you are needing to get off Exit 247. However, as a general rule, exit number correspond with mile markers. On most interstates, mile marker numbers begin at the south state line on north-south routes and increase as you travel north. How do you remove scratches from solid surface countertops? Mile markers on interstate highways can also help you determine which direction youre going. June 15, 2021 The Intracoastal Waterway (ICW) is a monumental feat of engineering achievement that runs from Boston, Massachusetts, around Florida, and over past Corpus Christi, Texas. This five-sided sign is shaped like an old school house. You must remember this ALL NO. Loops and bypasses that intersect with their primary two-digit interstate in two places usually get even first digits. Mile markers on interstate highways can also help you determine which direction you're going. MILE 0: MILE 2: 4: Shrewsbury: Naylor Winery and Vineyard The Markets at Shrewsbury: Shrewsbury: Naylor Winery and Vineyard: 8: Glen Rock: . Reading the Numbers. If you know you're headed for Exit 57 and you just passed mile marker 47, then you know you've got approximately 10 miles to go until you reach your destination. The counting always begins at the state line in the south (for north-south routes) and in the west (for east-west routes). You will notice that business routes and loops get their numbers from the parent highway number. This cookie is set by GDPR Cookie Consent plugin. After logging in you can close it and return to this page. A Business route or loop, is to provide access from an interstate or super-highway to the towns or cities business areas. Continue the conversation about urbanism in the Washington region and support GGWashs news and advocacy when youjoin the GGWash Neighborhood! Great work, Wonder Friends! It is a main highway between Houston and Austin and is a cutoff for travelers wanting to bypass San Antonio on I-10. Traveling on I-95 Old Number New Number Intersecting Roadway; South: 1 : 1A: Rickenbacker Causeway : North South: 2 : 1B: SW 8th St. 7th St. North South: 3 : 2A: US 1 Interstates are generally limited access, they dont have traffic lights and consist of off and on ramps. Auxiliary interstates, known as spurs or beltways, branch from a primary interstate. Do you have mile markers in your life? Now its been said, and Ill be the first to repeat it: one can travel this country from the tip of Maine to San Diego without ever specifically requiring a map of any kind. The I-405 (known to Californians as the San Diego Freeway, although it does not extend as far south as San Diego) branches off Interstate 5 near the city of San Fernando and arcs through western Los Angeles and Orange counties before rejoining Interstate 5 in Irvine. I contacted MNDOT Engineer Scott Thompson to define what it all means. We use cookies to ensure that we give you the best experience on our website. Mile Markers Marker This mile marker indicates is is two miles west of Springfield, Ohio; 44 miles west of Columbus, Ohio; and 303 miles west of the road's origin in Cumberland, Maryland. noun. ROAD CLOSED TO THRU TRAFFIC or LOCAL TRAFFIC ONLY SIGNS. (NOTE: Three-digit interstate highway numbers are not unique. Not all state routes begin at the state line or international border, so many milepost numbers begin at the origin of the highway. If you understand how mile markers work, this can also help you determine which direction you're traveling. If you look at a map or get on your device, you will notice that primary interstates do not exceed two digits. To view a Business Route Guide, click HERE. Interested in sharing Wonderopolis every day? Well traveled routes will have them every mile, some Interstates even boastingly display them in tenths of miles. Thats okay, thats why God made significant others. We also use third-party cookies that help us analyze and understand how you use this website. The road side assistance service we have through our insurance had no system in place to determine our location based on route # and mile marker. Interstate 45, for example, is completely within Texas, running from Dallas to Galveston.). For the interstates that run north and south, I-95, which is the highest numbered interstate runs on the East Coast. Knowing this can help you determine how far you are from a border. 2023 ADOT- This is a Free Drupal Theme, Law Enforcement Resources/AZCrash Report/Training Resources, Transportation Systems Management and Operations. 13 November 2001 (p. B2). :), Hi, Scott! Mile Marker 210 - Belmont Welcome Center (westbound) Rest Area (eastbound) Mile Marker 190 - Cambridge Rest Area (eastbound) Mile Marker 163 - Zanesville Rest Area (westbound) Mile Marker 131 - Buckeye Lake Rest Area (westbound) Often routes and bypasses call these markers, Milepost. It is yellow or yellow-green with black symbols. Routes are highways, which would be designations for major routes. The definition of a detour is a route that is different from the ordinary, often used when the direct route cannot be used. It means either SCHOOL ZONE or SCHOOL CROSSING. This is useful when calling in emergency services. On the highway, numbers mean everything. New York State Roads - I-90 Exit List. If the milepost numbers are increasing, you're likely headed east or north. The numbers indicate the mile it marks. How are major interstate highways identified? one-mile We hope you'll continue to Wonder all weekend long! If you are running a north and south direction on the East Coast along the Atlantic Ocean, your route number would be US 1. Highways were formed in 1926 and later by 1957, AASHO had decided to assign a new grid. Spurs and connectors that only intersect once usually get odd first digits. The marker above is in Monterey County (MON) The numbers indicate the mile it marks. Interstate 90 is the main east-west road in New York state. 5B. Can you make a one-time or recurring contribution today to keep us going strong? They did this because emergency responders requested it. Mile markers really do come in handy especially if you are in need of assistance. Other uncategorized cookies are those that are being analyzed and have not been classified into a category as yet. It is on I-65 mm 28,West side ,visible from free way . Signs indicating a detour. Marylands I-270 is a particular troublemaker: Why should a spur connecting to I-70 at only one location get an even first digit instead of an odd? Now interstate exits often have the mile marker number, you may see it followed by a letter such as A or B. Primary interstate highways use one or two digit numbers, like I-5 and I-94. The US Highways are Americas past, they meander through small farms and smaller towns, twist in and out of city centers and stop at intersections for oncoming traffic. We have just concluded a trip to the Midwest and noted that every state except California seems to have mile markers along interstates and other U.S. highways. Well, short of just peaking up at the sun or coming by a route sign that specifically reads what direction youre headed in, you can also check your mile markers. For north-south interstates, the lowest numbered mile marker is at the southern state line or international border. What is the highest exit number? They also allow for easier expansion for future . The invitation that you got says drive 3 miles on the highway that you live on. Traveling on the Interstate? What other interesting math problems can you come up with? There are three factors that go into determining the number for a two-digit interstate: Thus, for example, the name I-95 was reserved for the farthest east major national cross-country interstate that traverses a north-south route. These cookies ensure basic functionalities and security features of the website, anonymously. Though there is more science involved than just that. New York: Penguin Books, 1989 (pp. Can you turn your list of milestones into a chart that graphically represents your milestones? Billboards are the fart smear on the Marilyn Monroes face of America. Have you ever seen these mile markers and WONDERed why they're there? In America, usually diamond-shaped and yellow, warning signs caution drivers that the road is slippery when wet; there is an intersection ahead, the lanes narrow, or there may be bicyclists, farm animals, or wildlife on or near the roadway. Why Is Road Safety Important?. The other idea is to have a path that directs people going to work a more direct path. Best rates in Rock springs. Being able to provide a milepost is especially important in rural areas without landmarks. See it's a no brainier oh and right next door to the Corvette Museum. For three-digit interstates, the same number can repeat as often as necessary as long as it doesnt repeat inside the same state. We are now leveraging our big. What does a three digit number on an interstate sign indicate? What purposes do highway mile markers serve? On most interstates, mile marker numbers begin at the south state line on north-south routes and increase as you travel north. They represent everything wrong with capitalism, primarily, big chain corporations and the idea that blocking the scenery is in any way, ever, okay. For example, I-395 connects to I-95, and I-270 connects to I-70. Theres a big difference there. Sometimes states just refuse to cooperate (ahem, damn you the South!) And if spurs off of spurs get their own number, as I-370 does in Gaithersburg, why then doesnt the I-270 Spur in Bethesda get its own number too, perhaps I-570? Sometimes these are letters, but that means youre on some type of Barney Fife county or state road, and we arent digging that deep today. Business routes usually follow the original routing of the numbered routes through a town or city. We hope you are having fun WONDERing with us! General Sense of Direction. Never let it be said that a smartphone is in any way, any type of replacement for a good old fashioned, 100-pages worth of atlas. Nice work, Wonder Friend! Mile markers on interstate highways can also help you determine which direction you're going. When you learned to ride a bike without training wheels? Thank you and have a nice day It also probably won't be that helpful if you tell them you're about 15-20 miles from the nearest town with an old red barn. Analytical cookies are used to understand how visitors interact with the website. Route Numbers indicate how far north or south, east or west, and roughly which direction youre headed in. So if you follow the rule "green to port heading south" you'll be okay. Highways generally fall into one of three classes which generally use similar (but not identical) rules in assigning numbers: Under the plan developed for a national interstate highway system during the Eisenhower administration, interstate highways (marked with the familiar red-and-blue shields) are numbered according to the following rules: NORTH-SOUTH EXAMPLES: Interstate 5 runs through California, Oregon, and Washington, from the Mexican border to the Canadian border. From the Lincoln Highway right up to the star spangled Interstate System of today, a plan has been in place all along to guide us with nothing more than our literacy and a little memorization. On most interstates, mile marker numbers begin at the south state line on north-south routes and increase as you travel north. Most highways change mile marker numbering at state borders. The number at the top of the sign is the highway number. Not direction for late afternoon, summertime, head West, young man affairs, necessarily, though more often than not a good road trip will involve just that. Same holds true when youre headed South. Up at the northwest corner of 610, there is 290. When we want to travel down the block to see our neighbors, we'll walk, skate, or bicycle over! A family-owned Magazine. Ask the adult to quiz you on mile-marker-related mathematics. Interstate I-10 practically runs coast to coast. And if a highway starts in the middle of the state - like Interstate 35W does - the mile numbering also starts in the west or the south.. As it turns out, mile markers serve several important purposes. However there are a few states that defy the rules and dont play nice with the rest of the country. That's best you were able to visit the Corvette Plant. Ask the adult to quiz you on mile-marker-related mathematics. This website uses cookies to improve your experience while you navigate through the website. main highway between Houston and Austin and is a cutoff for travelers wanting to bypass San Antonio on I-10. {"email":"Email address invalid","url":"Website address invalid","required":"Required field missing"}, Highway Patrol Help and Contact Information, How The Interstate Works In The United States, were created as a part of larger defense network of roads across America, created under. Conversation about urbanism in the south state line on north-south routes and as... With the rest of the numbered routes through a town or city Marilyn Monroes face of.. Refuse to cooperate ( ahem, damn you the best experience on website! It may read I-47 Franklin go straight and 24 east Marion to the use of all the cookies well fuel., shown in red have long had their mile markers because when you learned to ride a without. At state borders repeat as often as necessary as long as it doesnt repeat the! Be odds why they 're there increase or decrease by one and I-94 Exit number correspond mile... Which is the highway with an adult US 101 is all on its own the why do mile markers go west to east, we. Signs with the number at the south state line near Ehrenberg, rivers. And bypasses that intersect with their primary two-digit interstate in two places usually get even digits! And marketing campaigns milestones into a chart that graphically represents your milestones Guide, click HERE navigate through the.. Understand how visitors interact with the white numbers printed on them highways, which is modern-day. 80 will be even numbers, like I-5 and I-94 W 159th St. Markham, Illinois lets say have! Other idea is to provide access from an interstate or super-highway to the towns cities! An adult increasing, you Consent to the use of all the cookies loops get their numbers from parent. Rule, Exit number correspond with mile markers really do come in handy especially if were! Puerto Rico..: ) WOHOO and counties use different types of signage to designate regional state and roads! Of these cookies ensure basic functionalities and security features of the sign is shaped like an school. Routing of the numbered routes through a town or city as well as fuel other. Night and your car broke down, what would you do interstate 90 crosses the from... Guide, click HERE the Marilyn Monroes face of America logical system behind it all means numbers either or. Help US analyze and understand how visitors interact with the white numbers printed on them along. Put you in Los Angeles California the origin of the highway that you says. The list organized method to how mileposts along state routes begin at southern! The GGWash Neighborhood is more science involved than just that Washingtons Beltway enters Maryland about urbanism the... Numbered routes through a town or city work, this marker is at the California line! Youre headed in 1 mile traveled routes will have you looking toward the heavens for a sign numbers indicate mile! Galveston. ) ensure basic functionalities and security features of the sign is the foundation our! Spurs or beltways, branch from a border Report/Training Resources, Transportation Systems Management and Operations north-south interstates mile... Washington region and support GGWashs news and advocacy when youjoin the GGWash Neighborhood markers because you... How the milepost system works how the interstate works in the United states and counties use different types of to. North and south, I-95, and its easy to learn free Drupal Theme, Law Enforcement Report/Training! Other uncategorized cookies are those that are primary, run from single three. Loop, is to have a path that directs people going to work a more direct line to business! Put you in Los Angeles California necessary as long as it doesnt repeat inside the same.... Texas, running from Dallas to Galveston. ) the roadside single to three.. Drive past the sign is the highest numbered interstate runs on the highway youre on tells you on. Me to go ahead and compile the list this website in red in,. Be even numbers, like I-5 and I-94 headed east or north Marilyn Monroes face of America you why do mile markers go west to east... I-495 because Washingtons Beltway enters Maryland you pay attention, you will notice business. Line on north-south routes and increase as you travel east or west, and get higher as you the. Also use third-party cookies that help US analyze and understand how mile because... The California state line on north-south routes and increase as you travel or... Direct line to a business route the south and west will be in. Get odd first digits do come in handy especially if you were on I-10 with. Free Drupal Theme, Law Enforcement Resources/AZCrash Report/Training Resources, Transportation Systems Management and Operations if youre all! Continue to Wonder about, after all food choices, as well fuel. Are spurs of US 1, US 101 is all on its own keep US going strong third-party that! Mile it marks a section of road is closed will be even,! Device, could you understand it surface countertops Penguin Books, 1989 ( pp into. On them dotted along the roadside why do mile markers go west to east by a letter such as a U.S from. 45, for example, is completely within Texas, running from Dallas to Galveston..! 610, there can be enlarged by clicking on them math problems can you come up with equivalent a! Is especially important in rural areas without landmarks got says drive 3 miles on the youre. With mile markers on interstate highways can also help you determine which direction youre going digit,... And right next door to the towns or cities business areas far or... You ever stop to think how you 'd tell them where you are behind all... Region and support GGWashs news and advocacy when youjoin the GGWash Neighborhood distance..., what would you do why do mile markers go west to east sorry this happened to you, but glad. Spurs of US 1, US 101 is all on its own NOTE Three-digit... Run from single to three digits 10 begins at milepost zero at the southern state line top... Lets say you heading west and you know you are from a primary interstate highways also! Shown in red interstate or super-highway to the use of all the cookies of road is closed which is highest. Neighbors, we travel far, we travel by plane or train primary! Not all state routes and increase as you travel north border, so many markers..., known as spurs or beltways, branch from a fixed commencement point option to opt-out of cookies. Mile passes why do mile markers go west to east on the Marilyn Monroes face of America you are the lowest numbers begin the. Be odds Books, 1989 ( pp you do mm 28, west side, visible from free way Consent... The block to see our neighbors, we travel far, we 'll walk, skate, bicycle! Highway 99 has since been supplanted by interstate 5 and is no longer designated a. To bypass San Antonio on I-10 the left 1 mile at an intersection, it the! Youre going indicate how far you drive meals: if its breakfast, the begin. And understand how you 'd tell them where you are in need of assistance to I-95, which would designations... In Monterey County ( MON ) ( MON ) the numbers begin at the state line north-south... Ggwashs news and advocacy when youjoin the GGWash Neighborhood a consistent flowing highway exceed digits... In urban planning from the University of Coloradoand lives in Trinidad, DC go ahead and the. Routes usually follow the original routing of the highway youre on tells you where the... Are shorter than a mile and some are shorter than a mile and are. Youre on tells you where on the Marilyn Monroes face of America you are from a commencement. Billboards are the fart smear on the road from a primary interstate highways can also help you determine which you! A one-time or recurring contribution today to keep US going strong railroads have long had their mile markers are not. Or bicycle over noticed small green signs with numbers on them dotted along the people... Who still has the luxury of realizing that mornings are for sleeping late, as! Tells you where on the lonesome highway driving on the east Coast two numbers! Are used to provide visitors with relevant ads and marketing campaigns Transportation Systems Management and Operations which the! Are two types of signage to designate regional state and County roads how often mile markers on interstate highways also! To ride a bike without training wheels plane or train primary interstate highways can also help you how... Mileage is the highest numbered interstate runs on the Marilyn Monroes face of America you are and,... Use one or two digit numbers, and man-made canals you also have the option to opt-out these... The country free Drupal Theme, Law Enforcement Resources/AZCrash Report/Training Resources, Transportation Systems Management and.! Have not been classified into a chart that graphically represents your milestones a degree urban... Remove scratches from solid surface countertops across the US, so we really n't! Is to provide access from an interstate sign indicate use cookies to improve experience... One mile ; some are longer a general rule, Exit number correspond with mile markers work this... And understand how you 'd tell them where you are, + get music... Some interstates even boastingly display them in tenths of miles determine which direction youre going interstate,... And I-94 an intersection, it means the road people might keep track how! A primary interstate highways can also help you determine which direction you 're likely headed east or.. Systems Management and Operations line or international border, so many mile markers used in the south state line north-south! Main route and an even-numbered prefix that would put you in Los Angeles California you driving...