Harbor Boulevard runs in Orange County from Costa Mesa through the cities of Fountain Valley, Santa Ana, Garden Grove, Anaheim, Fullerton, and La Habra.

This extension would provide an alternate route for commuters coming from Orange County as they were limited to Hacienda Road, Brea Boulevard, and SR 57 at the time.

This portion was also formerly part of SR 72, but this segment was later relinquished to the cities of Anaheim, Fullerton, and La Habra.

[6] North Harbor Boulevard, where it rises from La Habra and passes over the Puente Hills, follows the historical route of the 1769 Portolà expedition, first Europeans to explore inland California.

They were stopped at the intersection of Harbor Boulevard and Ball Road by a line of riot police and officers on horseback.