Rule of thumb for side walks, they become usually more common when closing in on a point of interest ie a park, mall, or downtown area in most Texas cities. The real reason for the lack of sidewalks is that Texas is spread out compared to most of the rest of the country. Our cities mirror this as well. Thus, it is more normal to see people take cars mostly everywhere since nothing is located near enough to each other or within walking distance. Though this is not always true. When I lived in Denton (a few miles north of Lewisville), I lived in apartment complex that was close enough to a mall called the Golden Triangle Mall which has a Barnes and Noble. Since I prefer walking over driving, I'd usually just walk to the Barnes and Noble even with the heavy construction going on there when I was living at the complex.
Most Texas cities have no real rhyme or reason in planning or style thanks to most of the construction really taking place after twentieth century oil boom that startled at Spindletop in 1901 and the invention of air conditioning. Before those two events, most Texas buildings were designed to trap cool air and were kind of small due to Texas not being that rich. We were rich in land though, and that's what people wanted in Texas: land. After the money from oil and the invention of centralized air, people built whatever they liked unless they were planned communities such as the Woodlands or Flower Mound which have stricter building codes.
