Why was CA-150 truncated in length?

[Quillz]

A long time ago, CA-150 was a much longer route. While its eastern terminus was always in Santa Paula with CA-126, the western terminus used to be near Los Olivos at US-101. It almost entirely encompassed what is today CA-154 and 192.

My question is, why? What was the reasoning for breaking up CA-150 into two more routes? Wouldn't having three routes traversing the Santa Paula-Los Olivos corridor be more confusing than a single, longer route?

[TheStranger]

A long time ago, CA-150 was a much longer route. While its eastern terminus was always in Santa Paula with CA-126, the western terminus used to be near Los Olivos at US-101. It almost entirely encompassed what is today CA-154 and 192.

My question is, why? What was the reasoning for breaking up CA-150 into two more routes? Wouldn't having three routes traversing the Santa Paula-Los Olivos corridor be more confusing than a single, longer route?

With regards to Route 154, I think it stands out on its own as a shortcut between Santa Maria and Santa Barbara (as opposed to the longer US 101 routing), rather than being the same corridor as the indirect, winding road to Santa Paula (much more quickly accessed via 101/126).

[The High Plains Traveler]

Until the 1964 renumbering, CA-150 went west from the Lake Cachuma area through Buellton and Lompoc, terminating at the ocean at Surf. This piece is what became CA-246 in the renumbering while CA-154 was assigned to the highway from Santa Barbara to Los Olivos. I haven't dug to see what the pre-1964 LRNs were but I think the piece from Lake Cachuma to U.S. 101 through Los Olivos was an unsigned state highway.