In the first few decades of the 1900s, Minneapolis began to lose its dominant position in the flour milling industry. Kansas City and Buffalo became centers of the milling industry instead. After 1930, the flour mills gradually began to shut down. The buildings were either vacated or demolished. By 1965, the last mill was shut down and river and rail use decreased drastically. To continue economic use of the river, civic leaders pushed for plans to build locks and dams, making the Mississippi River navigable past St.Anthony Falls for the first time. Minneapolis' population soared from 200,000 in 1900 to over 521,000 people in 1950. The main growth of the city was in part due to an organized streetcar system that ran down important roads across the city, encouraging high density. However, this system was dismantled in the 1950s and 1960s and highways were built throughout the city. An excellent example of this is the destruction of the Gateway district in Downtown Minneapolis. The neighborhood was known as a slum and therefore the neighborhood, and 1/3 of buildings in Downtown Minneapolis were leveled. You can see examples of these changes in the video below:
This period also brought with it great political and social change. A major figure for this change was Hubert Humphrey who led to the merging of the Minnesota Democratic Party with the Farmer-Labor Party. Humphrey is famous for serving as Mayor of Minneapolis, where he created a civil rights commission that addressed employment discrimination, which was emulated across cities in the country. Humphrey was elected to the Senate in 1948 and became Vice President to President Johnson in the 1960s.
Information sourced from Wikipedia. Cover image by w:en:User:Mulad and sourced from Wikipedia (available in the Public Domain)