The Michigan Department of Transportation (MDOT) is a constitutional government principal department of the US state of Michigan. The primary purpose of MDOT is to maintain the Michigan State Trunkline Highway System which includes all Interstate, US and state highways in Michigan with the exception of the Mackinac Bridge. Other responsibilities that fall under MDOT's mandate include airports, shipping and rail in Michigan. The predecessor to today's MDOT was the Michigan State Highway Department (MSHD) that was formed on July 1, 1905 after a constitutional amendment was approved that year. The first activities of the department were to distribute rewards payments to local units of government for road construction and maintenance. In 1913, the state legislature authorized the creation of the state trunkline highway system, and the MSHD paid double rewards for those roads. These trunklines were signed in 1919, making Michigan the second state to post numbers on its highways. The department continued to improve roadways under its control through the Great Depression and into World War II. During the war, the state built its first freeways. These freeways became the start of Michigan's section of the Interstate Highway System. Since the mid-1960s, the department was reorganized. It was renamed the Michigan Department of State Highways for a time. Further changes culminated in adding all modes of transportation to the department's portfolio. In August 1973, the department was once again renamed to the Michigan Department of State Highways and Transportation by executive order. The name was later simplified and shortened to that of today. History Early history The first State Highway Department was created on July 1, 1905. The department was born out of the Good Roads Movement at the turn of the century. Bicycle enthusiasts as a part of the League of American Wheelmen pushed for better roads and streets. They also wanted to ensure that bicyclists could use these streets and roads free from interference from horsedrawn vehicles. This movement persuaded the Michigan State Legislature to form a State Highway Commission in 1892. Another law in 1893 allowed voters in each county to establish county road commissions. The attention of Michigan residents was turned to the good-roads movement by Horatio S. Earle, the first state highway commission. In 1900 he organized the first International Road Congress in Port Huron and even put together a tour of a macadam road. He even ran for the state senate in