When the Arroyo Seco Parkway opened, it was the first freeway in the Western United States. It became a new alignment of U.S. Route 66, and the old routing via Figueroa Street and Colorado Boulevard became U.S. Route 66 Alternate. The southern extension over the Los Angeles River to downtown Los Angeles also carried State Route 11 (which remained on the old route when US 66 was moved) and U.S. Routes 6 and 99 (which followed Avenue 26 and San Fernando Road to the northwest). The 1964 renumbering saw US 66 truncated to Pasadena, and SR 11 was moved from Figueroa Street (which became SR 159) to the Pasadena Freeway. Finally, the number was changed to SR 110 in 1981, when SR 11 between San Pedro and the Santa Monica Freeway (I-10) became I-110.