1900s	1910s	1920s	1930s	1940s	1950s	1960s	1970s	1980s	1990s	2000s

1920
First four-way red-yellow-green traffic light in Detroit (Fort at Woodward)

1922
The first practical snowplow is designed and built by Edward Levy in Munising

1923
Highway Department links the Upper and Lower peninsulas with state-owned ferry service at the Straits of Mackinac (ends in 1957 with the opening of the Mackinac Bridge)

1925
Approval of the first state gasoline tax, a levy of two cents per gallon

First Highway Department to use aerial surveys for highway design

1926
For the first time, state map includes mileage table showing distances between selected cities

1927
First yellow no-passing line used in Michigan