Here's a report cited by some of the main news outlets online.
"They are working in tandem to decouple the legal standing to vote from American citizenship.
As a result of these efforts, there are several municipalities in the United States that currently allow non-citizens to vote in local elections.
Moreover, legislation to allow non-citizens to vote has been introduced in a number of states and localities including Washington, D.C., San Francisco, and New York City."
Allowing Non-Citizens to Vote in the United States? Why Not | Center for Immigration Studies