1. On April 20, 1836, the Territorial Legislature of Wisconsin approved the charter for the Wilmington and Fox River Canal Company, a project designed to connect the Fox River with the Illinois and Michigan Canal. Despite funding and legal obstacles, the canal was finally completed in 1854, and was an important transportation route for many years.

2. On April 20, 1862, the Battle of Island Number Ten began during the American Civil War. This battle, which took place in the Mississippi River, was a major victory for Union forces and led to the capture of a significant portion of Confederate troops.

3. April 20, 1905, is the birthday of Earl H. Behrens, a Wisconsin-born inventor who co-founded Behrens Manufacturing Company, which specialized in the production of steel containers used in a variety of industries. Behrens was also an accomplished musician and composer, and wrote several popular songs.

4. April 20, 1940, marks the founding of the Wisconsin State Patrol, which was established to provide law enforcement and traffic safety services for the state's highways. Over the years, the State Patrol has expanded its responsibilities to include specialized units such as the K-9 unit and the Motorcycle Unit.

5. On April 20, 2016, Wisconsin Governor Scott Walker signed a bill legalizing the use of cannabidiol (CBD) oil for medical purposes. CBD oil is derived from the hemp plant and has been shown to have a variety of health benefits without the psychoactive effects commonly associated with marijuana. The bill was widely supported by medical professionals and patients who suffer from conditions such as epilepsy and multiple sclerosis.