Separating these two towns and surrounding the entire area was a primarily rural landscape. Tree farms were dominant - mostly of the citrus and walnut variety.
Many of the executives of Hollywood and Los Angeles lived in the surrounding rural San Fernando and San Gabriel Valleys. These well-to-do types liked the comforts and seclusion of country living. There was a problem, though. It took considerable time driving back and forth over windy canyon roads from home and work. So, they came up with a brilliant idea.
So, a couple of freeways were built. All was wonderful.
In fact, the executives figured out that real-estate values went way up. They decided to take advantage of the situation.
Arteries were constructed. Almost instantly, gas stations and restaurants were built where the arteries met the freeways. Gone were many of the orange groves. People moved near these arteries to take advantage of the superfast freeways.
Soon, the executives got a little concerned.
Eventually, Southern California became a big urban mess. It turns out, adding freeways only adds too many people and more congestion than before.
Of course, the executives moved to escape the concrete jungle to nice rural communities like Denver and Phoenix.
People can be really stupid.