A streetcar suburb is a residential community whose growth and development was strongly shaped by the use of streetcar lines as a primary means of transportation. Early suburbs were served by horsecars, but by the late 19th century cable cars and electric streetcars, or trams, were used, allowing residences to be built further away from the urban core of a city. Streetcar suburbs, usually called additions or extensions at the time, were the forerunner of today's suburbs in the United States and Canada.