Just look at the signage in the Detroit Metro Airport, it’s in Chinese and English. The traffic is mainly due to the connections in the auto industry and supporting businesses in the US and China.
“The traffic is mainly due to the connections in the auto industry and supporting businesses in the US and China.”
Yep. Bingo.
“Detroit” itself shrunk, but its suburbs are very large. Metropolitan airport (20 minutes sw of Detroit) is big and (was) a busy major hub.