Many of us rely on our cars to get from point A to point B every day, which means it’s rare for us to find ourselves alone on a highway. The Interstate Highway System was created in 1956, and since then, the U.S. has built a vast network of ever-busier roads, carrying commuters, vacationers, and commercial traffic alike. But have you ever stopped to wonder which roads are the busiest? Luckily, the Federal Highway Administration (FHWA) has compiled a list of the country’s busiest roads, based on a metric the agency calls Annual Average Daily Traffic (AADT). Read on to learn which routes rank in the top 10 busiest highways in America.
10. Interstate 90 – Chicago, Illinois
Interstate 90 — the longest route in the Interstate Highway System — stretches from Boston to Seattle, covering a distance of 3,021 miles. Driving the entire length of I-90 would take you approximately 50 hours, and you’d travel through 13 states, including New York, Pennsylvania, and Idaho. However, you should be prepared for possible delays as you drive through Chicago. An estimated 321,700 vehicles use the Windy City’s segment of I-90 each day, making it the 10th-busiest highway in the nation.
9. Interstate 15 – Las Vegas, Nevada
Interstate 15 was originally intended to begin in San Bernardino, California, located east of Los Angeles, but the decision was later made to extend its origin south to San Diego. Today, the highway runs north for 1,433 miles to the Canadian border, where it joins Alberta Highway 4. A 124-mile stretch of I-15 through Nevada passes right through Las Vegas. Its proximity to the Strip, along with its connection to Los Angeles and Sin City, makes this a busy segment of road for tourists and business travelers alike. The Vegas section of I-15 sees approximately 332,000 vehicles every day.
8. Interstate 95 – Miami, Florida
Driven by commerce and vacationers alike, Interstate 95 passes through 16 states, more than any other U.S. highway. It runs the entire length of the East Coast, from the Maine-Canada border to Florida. As such, it is a popular route for so-called “snowbirds,” those who head south for warmer winters. I-95 ends in Miami, where it becomes U.S. Highway 1 — aka the Overseas Highway — and continues to Key West, home to the southernmost point in the contiguous U.S. The terminus of I-95 in Miami is Florida’s — and one of the nation’s — busiest stretches of highway, with 339,500 average daily vehicles.
7. California State Route 60 – Los Angeles, California
California State Route 60 is the only highway that ranks in the top 10 busiest highways that is not an interstate highway. The route is also known in parts as the Pomona Freeway and the Moreno Valley Freeway. It runs east from Los Angeles along the southern side of the San Gabriel Valley to meet I-215 in Riverside. L.A. traffic is notoriously heavy, and CA-60 is no exception. It is one of five L.A. highways to appear on this list and sees 350,000 vehicles each day.
6. Interstate 10 – Los Angeles, California
Interstate 10 is the main interstate crossing the southern U.S. From where it meets California Route 1 in Santa Monica, I-10 extends 2,640 miles to Jacksonville, Florida, including an 880-mile stretch that crosses Texas. That segment, however, isn’t the busiest on I-10. The honor belongs to the part of the highway that runs from the coastal city of Santa Monica, located west of downtown Los Angeles, into East L.A. Perhaps better known as the Santa Monica Freeway, it is one of the busiest commuter routes in Southern California, with an average of 355,000 vehicles per day.
5. Interstate 210 – Los Angeles, California
Running along the northern borders of Los Angeles, from the city of Sylmar to Glendora, is Interstate 210. Along the way, it passes through Pasadena, home of the annual Rose Bowl. The road, also known as the Foothill Freeway, measures less than 50 miles long. Despite its short length, I-210 is incredibly busy — with some 358,000 commuters driving along it every day.
4. Interstate 405 – Los Angeles, California
At just 73 miles in length, Interstate 405 is the main north-south artery through the city of Los Angeles, connecting Irvine in Orange County with San Fernando in the Valley. It is a key route from L.A. to the Port of Long Beach and Los Angeles International Airport (LAX). As such, “the 405” — as locals call it — is frequently named one of the most congested highways in the world. A local joke is that its name refers to the maximum speed — just four or five mph, thanks to the 383,500 vehicles trying to use the freeway on an average day.
3. Interstate 5 – Mission Viejo, California
Interstate 5 runs along the entire West Coast, connecting the Mexican and Canadian borders. The route also connects California’s three biggest metro areas —San Francisco, Los Angeles, and San Diego. The segment through Orange County, south of Los Angeles, is one of the busiest, particularly as it passes through the city of Mission Viejo. Here, local commuter traffic and longer-distance commercial traffic are often caught in congestion, with a daily average of 415,000 vehicles. A major construction project to widen the road is currently underway as of 2024.
2. Interstate 75 – Atlanta, Georgia
Like I-95, Interstate 75 is a major north-south route, connecting the Great Lakes to Florida via cities such as Detroit, Cincinnati, and Atlanta. The highway carries so much traffic that much of its Georgia portion is six lanes wide. In Atlanta, I-75 joins with I-85 for a 7.4-mile segment known as the Downtown Connector with a whopping 16 lanes. The large number of lanes is necessary, given that this is the second-busiest stretch of highway in the United States, seeing 419,516 vehicles on an average day.
1. Interstate 5 – Los Angeles and Santa Ana, California
Interstate 5 has already been mentioned as the third-busiest stretch of highway in the nation, but another segment of this notoriously congested highway makes an appearance at the top of the list. Just north of Mission Viejo, I-5 becomes the Santa Ana Freeway, linking Orange County to metro L.A. Several popular tourist attractions are also in this area, including Disneyland. When commuter and business traffic is combined with visiting vehicles, it adds up to the most congested road in the entire country, with 504,000 vehicles trying to drive it on any given day.
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