The New Haven Division buses follow routes that had originally been covered by <answer>trolley</answer> service. Horse-drawn steetcars began operating in New Haven in the 1860s, and by the mid-1890s all the lines had become electric. In the 1920s and 1930s, some of the <answer>trolley</answer> lines began to be replaced by bus lines, with the last <answer>trolley</answer> route converted to bus in 1948. The City of New Haven is in the very early stages of considering the restoration of streetcar (light-rail) service, which has been absent since the postwar period.
Buses in New Haven uses what kind of route for their service?
trolley