Nature formed the first highways – many roads built in the United States followed buffalo trails or river channels. In California, the Arroyo Seco route (from Spanish, meaning “dry gulch”) carried rainfall from the neary San Gabriel mountains into the Los Angeles River. Before it became a highway it was a wagon trail in the dry season, and with the rise of bicycles and automobiles was adapted for use by both. Designs for a major road connecting Los Angeles proper to Pasadena first intended a parkway, a relatively smaller, more scenic route, but those were expanded as the city became a car haven. Even with mixed use and through the Great Depression the road building continued.

On this day, December 30, in 1940, the Arroyo Seco Parkway opened – several narrow lanes going to and from Pasadena. It was the first highway completed in the Western United States, and the oldest one currently in service.

Offramps were placed at 90-degree angles to the roads – which was less of a problem when top speeds were limited to 45 miles per house and buses and trucks were not allowed on the road, and when it carried 27,000 vehicles a day, compared with today’s 122,000. Little has changed construction-wise from its first days – no banked ramps, no acceleration / deceleration lanes. Driving State Route 110 is like going back through time.