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More than 36 million drivers are expected to hit U.S. roads over the Memorial Day weekend with Congress stuck in neutral over plans to renew federal transportation funding.

The Department of Transportation’s Highway Trust Fund has been projected to run out of money as early as August without congressional action.

The traditional source of money for road and transit projects is the federal gas tax, which is currently priced at 18.4 cents-per-gallon. That tax has not been increased since 1993, however, and the legislation that authorizes the government to collect it is scheduled to expire on Sept. 30.