Prosperity returned in the 1940's. The state's dairy products were in demand, and shipbuilding became an important wartime industry. The opening of the St. Lawrence Seaway in 1959 made Milwaukee a world port. Meanwhile, in 1946 Wisconsin voters elected to the U.S. Senate Joseph R. McCarthy, whose anti-Communist activities during the early 1950's made him one of the most controversial figures in national politics.

Beginning in the late 1960's, social unrest in the state led to several troublesome incidents. There were disruptive civil-rights demonstrations in Madison and Milwaukee in 1969. In 1970 the University of Wisconsin in Madison was the scene of bombings by antiwar radicals. In 1975 Menominee Indians briefly occupied an abandoned abbey near Gresham, demanding that it be given to them for use as a hospital. Most of the unrest, however, had subsided by the late 1970's.

In the 1970's, Wisconsin had employment and income levels above the national average and experienced a growth in population due to migration into the state. The economy faltered during the recession of the early 1980's but rebounded strongly. The 1990 census showed continued growth in population, again due to migration into the state.

In 1996 Wisconsin passed a sweeping welfare reform law that had been under consideration for three years; it took effect in April 1998.