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Completion Date
Project Type
Roads & Rails

Pasadena-Los Angeles, CA

34 04 23.0 N, 118 14 02.0 W

Arroyo Seco Parkway

The 6.7-mile Arroyo Seco Parkway was the first freeway in the United States to be built as a state highway and the first freeway west of the Mississippi.

"[I]t takes courage to do a thing the first time, no matter how simple and obvious it may appear after it is done. And this, fellow citizens, is the first Freeway in the West."
- California Governor Culbert Olson at the freeway's dedication

With its landscaped embankments, limited access, and depressed roadway, Arroyo Seco Parkway (now known as the Pasadena Freeway) became the prototype of the Los Angeles freeway system. Motorists enjoy a scenic drive featuring landscaped embankments lush with native chaparral. The curving alignment traverses a chain of small parks shaded by sycamores and eucalyptus and exposed views of the snow-capped San Gabriel Mountains.

The experience gained by observing traffic operations on the parkway confirmed the value of acceleration/deceleration lanes and the minimum practical width for planted medians. The prohibition of cross-traffic provided additional driving safety and convenience.


  • This 6.7-mile-long parkway was the first urban freeway to be built in the United States west of the Mississippi River.
  • Asphalt and portland cement concrete pavements were installed side-by-side for comparison purposes.
  • Despite having to carry over four times its projected design-year traffic, the parkway has remained in almost the same configuration as when it was opened in 1940.