I saw an article about open space preservation efforts in Newport Beach, and decided to look up the area on maps’ satellite view. Looking around nearby areas in Newport, Laguna Beach, Irvine, Tustin, Orange, etc, I realized: the timeline of residential development in central Orange County is actually visible.

• Newer neighborhoods have bigger houses than older ones.
• Older neighborhoods have varied muted colored roofs. Newer ones are almost all red tile.
• With some exceptions, older areas were built on flatter land & newer areas have crept into the hills, so grids are mostly older. The one newer area that’s flat-and-grid is all red tile roofs.

I don’t know how well it tracks for other areas. I’m less familiar with southern Orange County, for instance, and areas from Santa Ana northward into the LA Basin are much flatter and were largely built-up by the time I started paying attention.