Much of Interstate 805 was constructed from the late 1960s to 1975 along what was a largely rural route at that time. There was no original U.S. or state route along its route. However, with the explosion of development in Chula Vista and San Diego, the freeway now provides access to thousands of homeowners. The only portion of Interstate 805 to pass through land that was already extensively developed at the time of construction was through Mission Valley and Mid-City. A towering bridge leads the freeway across Mission Valley, while it follows the historic boundary between San Diego and East San Diego, which today are both part of San Diego. Boundary Street, the former dividing line, now acts as a frontage road for portions of I-805 between SR 94 and I-8.
Construction at the north end of I-805 improved the interchange where the Inland Freeway merges with Interstate 5. Underway from March 2002 through Fall 2007, this $176 million project expanded the exchange to a dual freeway configuration with truck bypass lanes, high occupancy vehicle lanes, and connections to SR 56.1 The northbound local bypass lanes were finished in early 2006, followed by opening of the southbound local bypass in Spring 2007.