The Allen Ranch, or Sam Allen Ranch, was one of the first and longest running ranches in the history of the state of Texas in the United States. The ranch was started a few years after the Texas Revolution in what is now southeast Houston and Pasadena. The ranch itself extended from Clear Lake to Harrisburg (in modern east Houston). The cattle range covered much of southeast Harris County and Galveston County covering many of the modern communities around Galveston Bay.