The Massachusetts Bay Transportation Authority bus division operates 151 bus routes in the Boston, Massachusetts metropolitan area. All routes connect to MBTA subway, MBTA Commuter Rail, and/or other MBTA bus services. Many routes are descendants of the streetcar routes of the Boston Elevated Railway, or of suburban companies including the Eastern Massachusetts Street Railway and Middlesex and Boston Street Railway. 147 routes are directly operated by the MBTA, while private companies operate four routes under contract. Four additional suburban operations are partially funded by the MBTA.