The great lakes cities were the wealthiest most influential region for a period of time. Go watch movies from the 80s. Detroit was the industrial heart of America.

There are lots of factors but broadly characterizing them as globalization is generally fair. Some included: The rise of japanese cars added competition but they were held at bay by import restrictions and the American preference for massive cars until the gas shortages in the 70s, the trend towards efficient capital meant most industrial firms switched to prioritizing their more profitable financing arms, Reagan liberalized international trade that let foreign imports into the US market, NAFTA moving manufacturing to mexico and canada, companies moving manufacturing to non union states in the south, then moving the parts supply chain abroad.