1. On March 23, 1848, Wisconsin held its first constitutional convention, which formed the basis for the state's government structure. The document was ratified by the U.S. Congress later that year and Wisconsin became the 30th state in the union.

2. The University of Wisconsin-Madison was founded on March 23, 1848, just three months after the state's constitutional convention was held. The university has since become one of the most prestigious public universities in the country, with over 45,000 students enrolled annually.

3. On March 23, 1979, the worst nuclear power plant disaster in U.S. history occurred at the Three Mile Island nuclear plant in Pennsylvania. Although located in Pennsylvania, the disaster had a profound impact on Wisconsin's nuclear power industry, as it led to increased scrutiny and regulation of nuclear facilities across the country.

4. Legendary Wisconsin governor and progressive leader Robert "Fighting Bob" La Follette was born on March 23, 1855. La Follette served as governor from 1901 to 1906 and was a champion of workers' rights and democratic reforms.

5. On March 23, 1857, the Wisconsin Supreme Court issued its landmark decision in the case of Ableman v. Booth. The decision upheld the Fugitive Slave Act of 1850, which required that all runaway slaves be returned to their owners. The court's decision was controversial and helped to fuel the growing abolitionist movement in Wisconsin and the nation as a whole.