Almost every New York City subway line stops at 42nd Street:
The A-C-E (the blue line) to 42nd Street-Port Authority Bus Terminal, at 42nd Street and 8th Avenue (transfer available to the 42nd Street-Times Square Station)
The 1-2-3 (the red line) to 42nd Street-Times Square, at 42nd Street and 7th Avenue
The N-R-Q (the yellow line) to 42nd Street-Times Square, at 42nd Street and 7th Avenue
The 7 train (the purple line) to 42nd Street-Times Square, at 42nd Street and 7th Avenue, OR 42nd Street-5th Avenue (transfer available to the 42nd Street-Bryant Park Station), OR 42nd Street-Grand Central Station, at 42nd Street and Lexington
The B-D-F-M (the orange line) to 42nd Street-Bryant Park, at 42nd Street and 6th Avenue
The 4-5-6 (the dark green line) to 42nd Street-Grand Central Station, at 42nd Street between Park and Lexington Avenues