NPR has a good story about the consequences of the loss of population in Niagara Falls, New York:
Niagara Falls used to be one of the biggest cities in New York. But since the 1960s, its population has fallen by more than half. Now, Niagara Falls must stay above 50,000 residents or lose its status as a city — and millions in state and federal funds that act as life support. As the 2020 census looms, city leaders are bracing for the worst, while experimenting with new ways to attract residents.