The 10 Longest Highways and Interstates in the USA

The longest highway in the United States is U.S. Route 20, which runs roughly 3,365 miles from Boston, Massachusetts to Newport, Oregon. Among Interstates, the longest is Interstate 90 at about 3,020 miles. Below is an accurate ranking of the longest roads in America — plus why their length matters for shippers moving freight out of Miami and South Florida.

The 10 longest Interstate highways

Interstates carry the majority of long-haul freight in the U.S. Here are the ten longest by approximate signed length:

1. I-90 — about 3,020 miles. Seattle, WA to Boston, MA, crossing 13 states. The longest Interstate.
2. I-80 — about 2,900 miles. San Francisco, CA to Teaneck, NJ; a primary coast-to-coast freight corridor.
3. I-40 — about 2,555 miles. Barstow, CA to Wilmington, NC; the main southern transcontinental route.
4. I-10 — about 2,460 miles. Santa Monica, CA to Jacksonville, FL; the southernmost cross-country Interstate and a key Sun Belt freight lane connecting South Florida to the Gulf Coast and West.
5. I-70 — about 2,150 miles. Cove Fort, UT to Baltimore, MD; the primary Midwest freight spine.
6. I-95 — about 1,920 miles. Miami, FL to Houlton, ME; the busiest north-south corridor on the East Coast and the lane every South Florida shipper uses to reach the Northeast.
7. I-94 — about 1,585 miles. Billings, MT to Port Huron, MI; the northern Midwest connector.
8. I-20 — about 1,540 miles. Kent, TX to Florence, SC; a secondary southern freight lane.
9. I-15 — about 1,435 miles. San Diego, CA to the Montana border; the primary inland West Coast corridor.
10. I-5 — about 1,380 miles. The West Coast spine from San Diego through Portland to the Canadian border.

What about U.S. Routes?

The Interstate system is not the whole picture. The older U.S. Numbered Highway System includes several roads longer than any Interstate: U.S. Route 20 (about 3,365 miles, Boston to Newport, OR), U.S. Route 6 (about 3,205 miles), and U.S. Route 30 (about 3,073 miles). These highways still carry significant regional, agricultural, and industrial freight — particularly in areas the Interstate grid skips.

Why highway length matters for shippers

Mileage drives transit time, fuel cost, driver hours-of-service planning, and freight rate. A load from Miami to the Northeast travels nearly the full length of I-95 — close to 1,900 miles — which typically means 2–3 days of transit and careful appointment scheduling at the destination. A cross-country move from PortMiami to Los Angeles follows I-10 for most of its 2,460 miles.

Understanding which corridor your freight rides helps you set realistic delivery windows, budget fuel surcharges accurately, and choose the right service mode — LTL for partial loads sharing a trailer with other shippers, or drayage for containers moving directly from the port.

The key freight corridors out of South Florida

For Miami and Port Everglades shippers specifically, three of these long Interstates are your primary outbound lanes:

• I-95 North — the default lane for freight moving to Jacksonville, the Carolinas, the mid-Atlantic, and the Northeast. Nearly every LTL carrier from Miami runs this corridor daily.
• I-10 West — connects South Florida to Tampa, New Orleans, Houston, and eventually Los Angeles. Critical for freight destined for Texas and the Gulf states.
• I-75 North — the inland alternative to I-95 for freight heading to Atlanta, the Midwest (connecting to I-40 and I-70), and the Great Lakes.

Container drayage from PortMiami and Port Everglades typically feeds directly onto these corridors, which is why drayage transit time and port pickup windows are the first bottleneck in any long-haul move out of South Florida.

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