What was the most populous city in the Americas in 2015?

São Paulo was the most populous city in the Americas in 2015 due to its rapid urbanization, economic growth, and immigration. The city has been a major center for industrial and commercial activities, attracting people from all over Brazil and abroad in search of employment opportunities. Its diverse economy and extensive infrastructure have made it a desirable destination for migrants, leading to a continuous increase in population. With its bustling metropolitan area, São Paulo has successfully established itself as a hub for finance, culture, and entertainment, contributing to its position as the most populous city in the Americas.