The Houston Zoo is often very crowded. It started...

The Houston Zoo is often very crowded. It started in the 1920s and the population of Houston has massively grown since then, while the zoo has a fixed size.

If you have a zoo pass, it's a great place to take the family. (Buying a one day ticket is ridiculously expensive) If you're an out of towner, you may want to consider a buying a City Pass.