Auto rickshaws are not allowed in South Mumbai (the area south of Bandra and Sion) primarily to control traffic congestion and maintain the historical character of the city's commercial heart. This restriction dates back decades and is supported by strong agreements with the local taxi unions, who have a long-standing monopoly in the southern districts. South Mumbai’s roads are often narrower and more "cramped" with high volumes of luxury cars and public buses; the erratic driving style often associated with three-wheelers is seen as a major potential cause for "gridlock" in these sensitive zones. Additionally, there is a socio-economic and "aesthetic" element, as the city has historically sought to keep the "SOBO" (South Bombay) area more aligned with a high-end, metropolitan image where black-and-yellow taxis are the primary form of small public transport. While rickshaws are the lifeblood of the suburbs, once you cross the "Laxman Rekha" (the boundary line at Bandra or Sion), you must switch to a taxi or the local train to continue south.