State Route 78, one of the original State Highways in the region, has has undergone many changes since it was originally built. Most of the original routing west of Vista, CA, known as Vista Way, has been eliminated by the current alignment of the highway. By the 1960’s, State 78 was an expressway west of Vista, CA. It was gradually upgraded further to a full freeway, bypassing or replacing yet more of the original alignment. Today, there are some original sections still around, albeit very short. The two main sections of old paving, mostly dating to the late 1920’s to early 1930’s, exists near El Camino Real and College Ave in the Oceanside area.
The first section, near El Camino Real, is located on Haymar Dr / S Vista Way and is only partly exposed. Here, the concrete has been repaved but is showing through some of the potholes.
To the east of this section, there is another and more exposed bit of old paving. Adjacent to the Marron Adobe on Haymar Dr (old Vista Way), this paving still retains the feel of the old roadway. No date stamps could be found, but the style of the concrete seems to date it from 1926 to 1935.
Other sections of older alignments do still exist, but they are all completely reconstructed and no longer retain the old paving.