Official Web site of the Metropolitan Transit Authority.
In 1974, the bus system in Houston was taken over by the city. And in 1979, the Metropolitan Transit Authority was formed as a regional system, serving all of Harris County. The last streetcars ran in 1940, although a new light rail system opened in 2004.
How the electric railways and private bus companies evolved into today's bus system within Houston.
Houston Streetcar History Pages
Jon Bell's Rail Transit Pages/Houston Light Rail
Metropolitan Transit Authority (Wikipedia)
The Bus Rosters Page
Information from "Houston Electric: The Street Railways of Houston Texas" by Steven M. Baron, and from the November 1969 issue of the magazine "Motor Coach Age".
Chicago Transit & Railfan Web Site