Is it farther or further?
1769, from French boulevard (15c.), originally "top surface of a military rampart," from a garbled attempt to adopt Middle Dutch bolwerc "wall of a fortification" (see bulwark) into French, which lacks a -w-. The notion is of a promenade laid out atop demolished city walls, a way which would be much wider than urban streets. Originally in English with conscious echoes of Paris; since 1929, in U.S., used of multi-lane limited-access urban highways. Early French attempts to digest the Dutch word also include boloart, boulever, boloirque, bollvercq.