We were just south of Dallas in the Corsicana area. There are steets named Katy in several of the small towns around there.
Most likely, those small towns are located near the old tracks of the Missouri, Kansas and Texas Railroad, also known as the Katy. Following the Civil War, railroads were a really big deal.
Nobody knows why the city of Katy is called Katy. Some say it was named for the railroad. Some say it was the name of a saloon keeper's wife..