Donald Cousens Parkway

Donald Cousens Parkway or York Regional Road 48, also referred to originally as the Markham Bypass or Markham Bypass Extension, is a regionally-maintained arterial bypass in Markham, Ontario, Canada. Named for former Markham mayor Don Cousens in April 2007, the route bypasses Markham Village (the original, historic downtown of Markham) and the preserved hamlet of Box Grove, it initially travelled northward from Copper Creek Drive, south of Highway 407, to Major Mackenzie Drive (York Regional Road 25). A southern extension to tie into Ninth Line (itself bypassing Box Grove) north of Steeles Avenue was later completed. In addition to its role of redirecting through-traffic around the two communities, the road serves as the boundary between the urban area of Markham and the protected Rouge National Urban Park to the north and east.

Construction of the route began in 2002 north of 16th Avenue. In 2004, an interchange with Highway 407 was constructed along with a connection north to Highway 7. Both segments and the interchange were opened by December of that year. The following year, construction began to connect these two segments as well as on the Box Grove Bypass along Ninth Line; the former opened in October 2006 and the latter in the spring of 2007. Construction of the most recently opened segment, connecting the Box Grove Bypass to the interchange with Highway 407, began in 2009. It opened after several delays in 2012 and included a realignment of 14th Avenue.

Donald Cousens Parkway and a planned connection with Morningside Avenue in Toronto form an "East Metro Transportation Corridor", originally envisioned by the province in the 1970s as a six lane municipal expressway. During the mid-1990s, the Ministry of Transportation of Ontario (MTO) conducted studies and identified the need for the corridor by 2011. Although York Region had intended for a continuous alignment, Toronto City Council has opposed the direct connection between Morningside and Donald Cousens Parkway. As a result, it is now proposed to connect Morningside Avenue and Donald Cousens Parkway via a widened Steeles Avenue and extend Morningside to Steeles further west near Tapscott Road.