Why did the Erie Lake of America become Dead Lake?

Tourism and fishing, both recreational and commercial fishing (primarily along the Canadian shore) are important elements of the economy of Lake Erie. During the 1960s, Lake Erie was declared a “dead lake” due to eutrophication and pollution.

a system in which products were made rapidly by machines

the option which was not a function of missionaries in the northwest was the first one - they established posts for trading furs and other goods.

missionaries were sent around the world to spread religion and their knowledge and others - they were not merchants who sold furs and other goods.