Dorchester is in Boston.
Dorchester (Dot) is the largest geographic and most populated neighborhood in the city of Boston. Home to Dot Ave., it is also Boston's most diverse neighborhood, with large pockets of African Americans, Irish, Vietnamese, Caribbean, and South and Central American residents. In recent years, the neighborhood has seen an influx of young working professionals, working artists (in areas like Lower Mills, Peabody Square, and Savin Hill), and a growing GLBT community along Dorchester Avenue, while it's still predominantly a working class neighborhood and a thriving center of immigration.
Although the JFK Presidential Library is in the neighborhood, Dorchester is generally not seen as a tourist destination. But if you are adventurous and would like to see a truly authentic neighborhood of Boston, it is the place. Generally the areas along Dorchester Ave. (serviced by the Ashmont branch of the red line subway) are your best bet to experience Dorchester's multi-cultural communities. Enjoy food at one of the many Vietnamese Restaurants in Fields Corner or many of the other Haitian, Jamaican, Central American, or Soul Food eateries along Dot Ave. Later, grab a drink at Dbar, Blarney Stone, Tavola Pizza, Ashmont Grill, or C.F. Donovan's or watch your favorite Gaelic football team over a few beers at The Banshee.
Red Line: The JFK/UMass, Savin Hill, Fields Corner, Shawmut, and Ashmont stations serve Dorchester, as well as the entirety of the Ashmont-Mattapan High Speed Line (a tramway that connects Ashmont station with other parts of the neighborhood). The Red Line splits into 2 branches after the JFK/UMass station: all stations except JFK/UMass are only served by the Ashmont branch.
The Uphams Corner and Morton Street stations on the Fairmount Line of the MBTA commuter rail are located in Dorchester.
Interstate 93 runs through the neighborhood: Exits 13, 14, and 15 serve Dorchester.
Although the neighborhood has improved considerably in recent years, it still has a reputation for being one of the most dangerous neighborhoods in Boston. Tourists should not venture in after dark unless they're completely sure of their destination, or are with a native.