DETROIT -- The U.S. Supreme Court has decided it won't intervene in a lawsuit that challenges the selection of a Detroit neighbourhood for a new bridge to Windsor, Ont.

Neighbourhood groups and the private owners of the Ambassador Bridge -- the aging span that currently links Windsor and Detroit -- claim the U.S. federal government violated environmental law, among other legal standards.

But the work of the Federal Highway Administration has been upheld by a federal judge and an appeals court.

The Supreme Court turned down an appeal in the lawsuit on Monday, saying it won't get involved.

Supporters of the new bridge between Windsor and Detroit say the structure could open by 2020.

A funding arrangement for the new bridge was announced last week, with Canada agreeing to cover the cost of building the bridge and a customs plaza on the U.S. side.

Authorities have said the limited capacity of the 85-year-old Ambassador Bridge and the Detroit-Windsor Tunnel, which is too tight for tractor-trailers, is an increasing impediment to trade.

The Ambassador Bridge handles one-third of all Canada-U.S. trade.