King's Highway 140, commonly referred to as Highway 140, is a provincially maintained highway in the Canadian province of Ontario. The highway connects Port Colborne near Lake Erie with Highway 406 in Welland, via the Main Street Tunnel. It was constructed in the early 1970s as part of the Welland Bypass project of the Welland Canal, which resulted in the severance of several highways and rail lines. Opened to traffic in late 1972, several months following the tunnel, Highway 140 has remained unchanged since, despite growing calls to resign it as an extension of Highway 406.