Browse mobile homes for sale in Fort Worth, TX. A mobile home, sometimes known as a trailer, is a prefabricated structure built in a factory and placed in a permanent site. Mobile homes can come in single-wide or double-wide. Single-wides are 18 feet (5.5 m) or less in width and 90 feet (27 m) or less in length and can be towed to their site as a single unit. Double-wides are 20 feet (6.1 m) or wider, and are 90 feet (27 m) in length or less, and are towed to their site in two separate units, which are then joined together.