https://www.nytimes.com/2021/09/20/nyregion/voters-dante-deblasio.html
The researchers were able to identify the voting records of the individual New York City voters by cross-referencing the New York State voter file — a list of every registered voter, whether they voted and their address — with the board’s cast-vote records, which contained hundreds of voting precincts where just one ballot was cast.
Those precincts included that of Mr. de Blasio, who is registered at Gracie Mansion, and that of Mr. Steel, a registered Republican who lives in NoHo, a heavily Democratic part of Manhattan.