In New York City, and in Washington, D.C., local ordinances once required electrified street railways to draw current from a third rail and return the current to a fourth rail, both installed in a continuous vault underneath the street and accessed by means of a collector that passed through a slot between the running rails. When streetcars on such systems entered territory where overhead lines were allowed, they stopped over a pit where a man detached the collector ("plow") and the motorman placed a trolley pole on the overhead. In the US, all these conduit feed powered systems have been discontinued, and either replaced or abandoned altogether.