Movable bridges, sometimes referred to as draw bridges, are an integral part of the transportation system and have proven to be an economical solution to the problem of how to carry a railroad line or highway across an active waterway. eir development has been in concert with that of (1) the development of the railroads and (2) the development of our highway system. In the United States, movable bridges are found most commonly in states that have low coastal zones such as California, Florida, Louisiana, Washington State, Virginia, New York, and New Jersey, or a large number of inland waterways such as Michigan, Illinois, Wisconsin, and Minnesota.