Have You Driven on the Longest Highways in America?

“The US Interstate System is unique. There is nothing like it in the world.”

Dan McNichol, from The Roads That Built America: The Incredible Story of the U.S. Interstate System Tweet

Few are as iconic as US Route 66 out of all the United States’ numbered highways. While this historic stretch of gravel was decommissioned in 1985, the modern interstate highway system continues to serve as an emblem of American freedom, mobility, and prosperity.

Today, the highway and interstate network encompasses over 41,000 miles, connecting cities and helping limit traffic congestion in key areas throughout the country. If you’ve been planning your next adventure, consider driving across or perhaps revisiting America’s longest highways.

A Brief History of America's Interstate Highway System

Before the rise of the automobile in the early 1900s, motorists relied on roads called “auto trails”, which served as early highways, but varied in quality and construction. While some auto trails were well-constructed, others were rough and poorly maintained. As the auto trail system became harder to manage, the U.S. Secretary of Agriculture began working with states to create a major road system that would go all the way across the country. Route 66 was one of the first major roads to be constructed in this manner. Unlike the earlier auto trails, it was designed to connect smaller towns and help farmers bring their crops to the markets.

The Federal Aid Highway Act of 1956, also called the Dwight D. Eisenhower National System of Interstate & Defense Highways, was created to set a standard for the national road and highway system. While the idea of an interstate system was pitched to Congress as a national security measure, it would ultimately have long-ranging effects on the US economy.

For example, interstate stretches made rural land more accessible and facilitated development in areas with limited economic prospects before being connected to a sophisticated highway network. The construction of interstates and highways attracted major companies to certain areas and helped spur growth.

The Federal Highway Administration (FHWA) plays a significant role in overseeing the planning, development, and expansion of the Interstate System. It works with state departments of transportation to ensure that interstate projects adhere to federal guidelines and standards.

Understanding Highway Terminology: Western to Eastern Terminus

In the highway system, “eastern terminus” refers to the endpoint of a highway or interstate route in the eastern US, representing the easternmost point of the highway where it meets another road, interstate, or significant landmark. For example, the eastern terminus of Interstate 90 is in Boston, where it meets with several other interstate highways and terminates at its intersection with US Route 1.

The “western terminus” refers to the endpoint of a route in the western part of the US. This represents the westernmost point of the highway where it meets another road, interstate, or landmark. For example, the western terminus of Interstate 10 is in Santa Monica, where it intersects with State Route 1 (Pacific Coast Highway) near the Pacific.

What is the Difference Between Highways and Interstates?

As the name suggests, an interstate crosses state lines. All interstates are highways but not all highways are interstates. Interstates typically use on and off-ramps instead of directly crossing other roads. This design feature helps maintain traffic flow by reducing the number of intersections and potential points of conflict. Interstates have fewer exits with ramps, more lanes, and higher speed limits to help traffic move faster.

Highways, on the other hand, often pass through towns and may have several turn-off roads, providing access to local communities, businesses, and residential areas. These turn-off roads, also known as intersections or exits, allow drivers to exit the highway and navigate through the town or access nearby destinations. Highways are designed to connect various regions and communities, so they frequently pass through towns along their route.

From the West Coast to the major Southern cities, here are some of the most epic highways and interstates in the US.

The Top 10 Longest Interstate Highways in America

1. Interstate 90 (I-90)

I-90 extends from Seattle, Washington, on the west coast, to Boston, Massachusetts, on the east coast. It spans approximately 3,100 miles, making it America’s longest interstate highway. It’s also worth the long drive, meandering through the scenic landscapes of the Pacific Northwest, Midwest, Mountain West, Great Plains, and Northeast.

While I-90 is often referred to as the only east-west highway to cross the state of Washington, there are, in fact, several routes and highways that do the same — US Routes 2 and 12, according to the Snoqualmie Valley Historical Museum. However, I-90 is the only highway to connect two of Washington’s largest cities, Seattle and Spokane. It’s the third busiest road in the Evergreen State with over 148,000 motorists driving by each day.

I-90 provides convenient access to Logan International Airport and Seattle’s Greyhound bus station. It is also the closest Interstate Highway to South Dakota, running east-west across the northern part of the state, providing access to cities like Rapid City and Sioux Falls.

For those in search of hidden gems off I-90, Old Sturbridge Village, Massachusetts, and Olde Avon Village, Ohio offer a rare glimpse into 19th-century life. The swimming beach at Lake Kegonsa State Park, Wisconsin is perfect for a family outing; the Eternal Flame Falls in Orchard Park, NY is an awe-inspiring natural phenomenon off the beaten path.

2. Interstate 80 (I-80)

I-80 is known as the “Highway to Heaven” — mile markers 6 to 28 are a visual marvel, with the road appearing to lead upwards to the sky. I-80 encompasses approximately 2,901 miles across the northern US, extending from downtown San Francisco, California, to Teaneck, New Jersey.

This east–west transcontinental freeway was one of the original routes of the Interstate Highway System and is the second-longest US interstate highway after I-90. It cuts through some of the most vibrant cities in the nation, including Des Moines, Oakland, Reno, Sacramento, Salt Lake City, and Toledo.

For anyone who wants a trip down memory lane, I-80 is the closest approximation of the historic route of Lincoln Highway. It also traces historically significant routes like the Oregon and California Trails; America’s first transcontinental airmail route; and sections of the country’s first transcontinental railroad.

3. US Route 20 (US 20)

Extending from Newport, Oregon, to Boston, Massachusetts, US 20 spans approximately 3,365 miles across a dozen states, making it the longest road in the country. The eastern terminus begins in Boston, Massachusetts while the western terminus is at Newport, Oregon. It runs parallel to I-90 and carries motorists across Idaho, Illinois, Indiana, Iowa, Montana, Nebraska, New York, Ohio, Pennsylvania, and Wyoming.

US Route 20 is not part of the interstate system and follows the older route numbering rules for American highways. Thrill seekers can explore local landmarks and attractions following historic 1926 alignments of Historic Route 20 via The 20 Tour. Moreover, motorists on I-15 can connect to US 20, which provides access to the western entry point to Yellowstone National Park.

4. US Route 6 (US 6)

US Route 6 is America’s longest contiguous highway, stretching unimpeded through 14 states and five state capitals. It reigned as the longest highway in the nation, running for 3,662 miles until the northward section from Long Beach to Bishop in California was decommissioned in 1965.

Today, it runs from Bishop, California, to Provincetown, Massachusetts, covering approximately 3,207 miles. It makes for a scenic drive, passing through farmland and ranch properties in California.

Travel + Leisure recommends stopping by the desert canyons and prehistoric archeological sites of Humboldt-Toiyabe National Forest in Sparks, Nevada. Overnight camping is allowed in select areas, where the dark, expansive skies are perfect for stargazing.

Road trip, anyone?

5. US Route 30 (US 30)

Stretching from Astoria, Oregon, to Atlantic City, New Jersey, US Route 30 spans approximately 3,073 miles, making it the third longest road in the US. First proposed as Lincoln Highway in 1925, it was the first paved transcontinental highway in the country. The first sections to be completed in Pennsylvania were opened in 1928. Almost two-thirds of the Lincoln Highway would later be designated US Route 30.

The route meanders through southern Pennsylvania and crosses the state border of Ohio, carrying motorists along many historic sites and areas. It runs parallel to Interstate 76 and the Pennsylvania Turnpike.

The brainchild of Indianapolis Motor Speedway co-founder Carl Fisher, some sections of US Route 30 still carry the name Lincoln Highway in places like Pennsylvania. Popular attractions off US 30 include Michaux State Forest, which is home to various species of oak, birch, and maple trees.

6. Interstate 10 (I-10)

Known as the Christopher Columbus Transcontinental Highway, I-10 is a coast-to-coast interstate that starts at the sun-drenched Pacific Coast in Santa Monica, California, and leads to the Atlantic Ocean at Jacksonville, “Florida’s Shrimp Capital”. It covers approximately 2,460 miles, making it one of the longest interstates in the country after I-90, I-80, and I-40.

This scenic interstate serves the southern US, stretching from Southern California the Desert Southwest, and the Southeast. It passes through Alabama, Arizona, Louisiana, Mississippi, New Mexico, and Texas.

I-10 was Los Angeles’ first freeway with a four-mile section having been constructed between 1933 and 1935. It is a major traffic corridor connecting Southern California with the Inland Empire and the desert communities of Palm Springs, Indio, and Phoenix. No I-10 itinerary is complete without a quick jaunt to the Santa Monica Pier or Joshua Tree National Park.

7. Interstate 40 (I-40)

As one of the longest interstate highways in the country, I-40 covers eight states and connects the Desert Southwest with the Southeast. Extending from Barstow, California, to Wilmington, North Carolina, I-40 spans approximately 2,555 miles throughout the southern US.

It is a major cross-country freeway that follows the historic alignment of Route 66 across the Mojave Desert. While they are not the same highway, I-40 often follows the path of the Mother Road in many places, allowing travelers to experience a sense of nostalgia.

I-40 cuts through New Mexico and converges with I-25 in Albuquerque. Major stops off the interstate include the Grand Canyon National Park, Mojave National Preserve, Petrified Forest National Park, and Route 66 Mother Road Museum.

8. US Route 50 (US 50)

9. US Route 60 (US 60)

Stretching from Brenda/Wickenburg, Arizona, to Virginia Beach, Virginia, US Route 60 extends for over 2,670 miles, crossing through the southwestern and southeastern United States. Commissioned in 1926, it is a major east–west highway that provides access to several hiking trails and fishing spots. Travel + Leisure suggests a visit to Cibola National Forest and National Grasslands; Kaw Lake; and Chesapeake Bay.

10. US Route 2

Known as “The Great Northern”, US Route 2 encompasses over 3,600 miles, connecting Everett in Washington to Michigan’s Upper Peninsula. A segment route runs separately from Rouses Point in New York to Houlton in Maine. This scenic route passes through vibrant cities, historic sites, lakes, mountains, and valleys.

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