Subway extensions refer to the expansion of existing subway systems to reach new areas, improving public transportation access. These projects often involve adding new stations and tracks, allowing more people to use the subway for their daily commutes. Extensions can help reduce traffic congestion and promote the use of public transit. Cities like New York City and Toronto have undertaken subway extensions to connect underserved neighborhoods. These projects typically require significant planning, funding, and community input to ensure they meet the needs of residents. Ultimately, subway extensions aim to enhance urban mobility and support economic growth.