What is the longest street in the United States?

Longest Street in the US: Colfax Ave vs Route 20

Discover the true champion behind the longest street in the United States by exploring famous continuous city thoroughfares versus massive cross-country federal highways. Understanding this distinction prevents common geography misconceptions and reveals fascinating American travel trivia worth knowing before your next road trip adventure.

What is the longest street in the United States?

Determining what qualifies as the longest street in the United States often sparks confusion, as people frequently mix up national federal highways with local municipal thoroughfares. Depending on whether you measure a continuous local city street or a cross-country federal route, the answer changes entirely.

To put it simply, U.S. Route 20 holds the title for the longest road in the US, while Colfax Avenue in Colorado is widely recognized as one of the longest continuous local streets in a single urban area.

U.S. Route 20: The Longest Highway Across America

When looking at official highway mileage rather than a city-regulated street name, U.S. Route 20 is the undisputed champion of length. Stretching over 3,300 miles from Boston, Massachusetts, all the way to Newport, Oregon, it cuts across twelve states and serves as a massive transcontinental corridor.

Most travelers do not realize that this highway breaks into two segments near Yellowstone National Park, but its total linear span eclipses almost every other named route in the country. Lets be honest: calling a 3,300-mile federal highway a street feels like a stretch to urban locals, yet geographic databases officially classify it under major road designations.

How Federal Highways Differ from Local Streets

Municipal streets are managed by city councils, feature local cross-streets, and usually have lower speed limits designed for urban commerce and transit. In contrast, U.S. routes are managed through federal and state transportation departments to connect major regions across state lines. Understanding this distinction clears up why mapping tools yield entirely different answers when searching for roads versus streets.

Colfax Avenue and Other Long Continuous City Streets

If you restrict the search strictly to local municipal streets that maintain a single uninterrupted name through an urban sprawl, Colfax Avenue in the Denver, Colorado metropolitan area emerges as a primary contender. Spanning roughly 26 to 50 miles depending on how local municipal longest continuous street in the US tracking is measured, it runs past historic neighborhoods, commercial districts, and open plains.

Other famous thoroughfares often contend for regional length records, such as Western Avenue in Chicago, which stretches over 20 miles and claims the title of the longest continuous street within city limits in Chicago. Yet, local boosters from various states frequently dispute these crowns due to shifting municipal boundaries and name changes.

Why City Street Claims Lead to Endless Debates

City planners frequently alter street names when roads cross county lines or incorporate suburban expansions, turning what was once a single path into a patchwork of named segments. This administrative reality is why checking maps carefully reveals that very few local urban streets maintain an identical name for more than a few dozen miles.

Comparing Long U.S. Roads and Streets

To understand the difference between national transit routes and local urban thoroughfares, it helps to look at their core structural differences.

U.S. Route 20 (National Highway)

Over 3,300 miles spanning from coast to coast across 12 states

Passes through rural expanses, small towns, and major cities alike

Federal highway system route maintained by state and national departments

Colfax Avenue (Local Continuous Street)

Roughly 26 to 50 miles depending on continuous municipal tracking

Completely integrated within a single major metropolitan area

Local urban thoroughfare and historical commercial corridor

Mapping Cross-Country Lengths: A Traveler's Discovery

Mark, a road trip enthusiast from Chicago, wanted to drive the absolute longest continuous federal route in the United States during his summer vacation.

He initially assumed an interstate like Interstate 90 was the longest, but quickly found himself confused by toll rules and changing highway designations.

After researching federal transportation maps, he discovered that U.S. Route 20 offered a non-interstate scenic alternative spanning all the way from Boston to Oregon.

He completed a portion of the route through Wyoming and Idaho, gaining a real-world appreciation for how vast and varied America's historic highway network truly is.