I cover all five New York City boroughs, each of which is also a New York State county:

Bronx Borough/Bronx County
Brooklyn Borough/Kings County
New York (Manhattan) Borough/New York County
Queens Borough/Queens County
Staten Island Borough/Richmond County

My office is in Brooklyn Heights, steps from downtown Brooklyn’s:

Kings County Supreme Courthouse
Brooklyn Historical Society
Brooklyn Public Library
Brooklyn Borough Hall and Brooklyn City Register Office
Three colleges and their libraries: Brooklyn Law School, New York City College of Technology (City Tech), New York University Tandon School of Engineering (formerly Brooklyn Polytechnic Institute)
New York (City) Transit Museum
U.S. Federal Courthouse, Eastern District of New York State (Counties: Kings, Nassau, Queens, Richmond, Suffolk; encompassing Long Island & Staten Island)

Just across the East River from lower Manhattan, I can also get to these locations very efficiently:

U.S. National Archives New York, Bowling Green, Manhattan
New York City: City Hall, Municipal Archives, departments of Buildings and Health, courts.
New York State court houses of 5 counties:

• Bronx
• Kings (Brooklyn)
• New York (Manhattan)
• Queens
• Richmond (Staten Island)

U.S. Federal Courthouse, Southern District of New York (Counties: Bronx, Dutchess, New York, Orange, Putnam, Rockland, Sullivan, Westchester)