A double-wide trailer is a pair of mobile homes constructed so that they can be connected together side by side. Modular homes that are transported in two or more parts to a site are often called double-wide trailers as well, but this is often an inaccurate designation.
A standard trailer, more accurately referred to as a mobile home, is a structure designed to be a permanent residence. It is no more than 18 feet wide and is built on a wheeled chassis for ease of transportation. A double-wide mobile home can be 36 feet wide once the parts are joined after transportation. Like standard mobile homes, double-wide mobile homes are almost completely constructed, inside and out, prior to transportation. Modular homes are usually unfinished on the inside and require additional construction on site.