Stretching 1,381 miles from Mexico to Canada, Interstate 5 is the West Coast’s workhorse highway—and a magnet for tall tales. Here are six myths even seasoned road‑trippers still repeat, along with the facts that set the record straight.
Myth 1: “I‑5 is the longest Interstate in the United States.”
It’s impressive, but not a record‑holder. At about 1,381 miles, I‑5 is barely half the length of I‑90, whose 3,021‑mile run from Seattle to Boston tops the Interstate charts.
Myth 2: “The Grapevine got its name from all those highway twists and turns.”
Drivers assume the nickname refers to the serpentine grade over Tejon Pass. In truth, Spanish explorers dubbed the canyon Cañada de las Uvas after finding wild grapevines there in 1772—long before any road existed.
Myth 3: “I‑5 hugs the Pacific coast all the way up the West Coast.”
The route parallels the ocean in the broad sense, but much of it—especially through California’s Central Valley—runs dozens of miles inland and even bypasses major coastal cities such as San Francisco.
Myth 4: “U.S. Route 99 vanished when I‑5 was built.”
While the federal designation was dropped in 1972, big pieces live on as state highways (California’s SR 99, Oregon’s OR 99, Washington’s SR 99) and local “Old 99” frontage roads that still shadow today’s freeway.
Myth 5: “I‑5 never closes for weather south of Oregon.”
Think again: snow routinely shuts the Grapevine section over Tejon Pass, sometimes for hours, stranding traffic between Los Angeles and the Central Valley.
Myth 6: “The speed limit is 70 mph all the way.”
Limits fluctuate with geography and state law—70 mph in rural Northern California, 65 (or even 55) through urban stretches of L.A. and Seattle, and just 60 mph across large sections of Washington.
