3 (New York City Subway service)

	Seventh Avenue Express
	A New Lots Avenue bound 3 train of R62s departing Pennsylvania Avenue
Northern end	Harlem–148th Street; 137th Street–City College (limited rush hour service)
Southern end	New Lots Avenue (daytime hours) ; 34th Street–Penn Station (overnight hours)
Stations	34; 33 (limited rush hour service); 10 (overnight service)
Rolling stock	R62; (Rolling stock assignments subject to change)
Depot	Livonia Yard
Started service	November 23, 1904
Route map
bypassed local section
91st Street
bypassed local section
66th Street–Lincoln Center
bypassed local section
28th Street
bypassed local section
Christopher Street–Stonewall
	Manhattan
	Brooklyn
	northbound only
	for 4 and 5 trains

The 3 Seventh Avenue Express is a rapid transit service in the A Division of the New York City Subway. Its route emblem, or "bullet", is colored red since it uses the IRT Broadway–Seventh Avenue Line through most of Manhattan.

The 3 operates 24 hours daily, although service patterns vary based on the time of day. Daytime service operates between 148th Street in Harlem, Manhattan and New Lots Avenue in East New York, Brooklyn, making express stops in Manhattan (between 96th and Chambers Streets) and all stops in Brooklyn. Limited rush hour service originates and terminates at 137th Street–City College instead of 148th Street. Overnight service short turns at 34th Street–Penn Station in Midtown Manhattan and does not operate to or from New Lots Avenue.

The 3 train formerly ran to City Hall or South Ferry in Manhattan, and was later rerouted to Flatbush Avenue–Brooklyn College in Brooklyn. In 1983, it was rerouted to New Lots Avenue.