US 99 ran from the Mexican border north to the Canadian border mostly near the present route of Interstate 5. It was one of the original US highways commissioned in 1926.

By 1928, US Highway 99 stretched from the Canadian border to Mexico, and was declared the longest improved highway in the nation. ... Bringing out Hwy 99's historic character holds promise, ...

Drivers could catch a glimpse of an old U.S Route 99 shield on Tuesday after part of a 5 Freeway sign fell down. The sign, located above the eastbound 134 Freeway at Victory Boulevard, usually ...