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U.S. Highway Coverage and Accessibility

The United States has an extensive public road system that totals approximately 4.17 million miles, including 220,516 miles within the National Highway System and 48,472 miles of interstate highways. These highways connect all 48 contiguous states and link all population centers and counties, offering excellent coverage in most cases.

However, trucking companies and drivers are concerned with “last-mile access,” or highway coverage between a freight terminal (factory, port, distribution facility) and the nearest major traffic corridor. This last-mile coverage remains lacking around many freight hubs, forcing trucks to use regular roadways that are usually narrower and more congested, causing safety and efficiency risks. “Last-mile shipments are often the least efficient leg of a freight trip,” a study by the Transportation Research Board finds, only exacerbated by the high volume of traffic near these sites.

Another feature that goes hand-in-hand with coverage is highway accessibility. While coverage is measured by the mere existence of highways in an area, accessibility is measured by the ability of travelers to use them to go where they want.

Highways are designed predominantly for private automobiles, so they tend not to accommodate public transportation or other modes of traffic. This proves to be especially problematic in urban areas, where highways divide continuous neighborhoods, displace pedestrian-accessible roadways and add to local congestion.

Researchers have increasingly pointed out their disproportionately negative impacts on minority and lower-income households in inner cities, advocating for replacing urban highways with multimodal roadways that are better suited for non-automobile travel demands and more equitable in traffic access.


Crowther, Ben, et al. “Freeways Without Futures,” Congress for the New Urbanism, 2021.

Highway Statistics 2020, U.S. Department of Transportation, Federal Highway Administration.

Litman, Todd. “Evaluating Accessibility for Transport Planning: Measuring People’s Ability to Reach Desired Services and Activities,” Victoria Transport Policy Institute, 15 July 2022.

Litman, Todd. “Introduction to Multi-Modal Transportation Planning: Principles and Practices,” Victoria Transport Policy Institute, 23 April 2021.

“The Last-Mile Access Problem,” National Cooperative Freight Research Program (NCFRP). Accessed 17 July 2022.

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