El Cajon Boulevard has a rich history. In the early 1900s El Cajon Avenue was the main wagon road connecting San Diego to the east county.
In 1937,the El Cajon Boulevard Civic Association hosted The El Cajon Boulevard of Progress Festival to celebrate the acceptance of the street as the terminus of Highway 80. In June of 1953, US 80 was transferred to the present routing of I-8, which was then called Mission Valley Rd.
Route 80 received its historic designation in 2006.