The Lexington Avenue Line is a major subway line in New York City, part of the New York City Subway system. It runs primarily under Lexington Avenue in Manhattan and serves the Upper East Side, Midtown, and Lower Manhattan. The line is designated as the 4, 5, and 6 trains, providing essential transportation for millions of riders each year. Opened in the early 1900s, the Lexington Avenue Line is one of the busiest subway lines in the city. It connects various neighborhoods and key locations, including Grand Central Terminal and Union Square. The line is known for its high ridership and frequent service, making it a vital part of the city's public transit network.