Trump promised $1 trillion for infrastructure, but the estimated need is $4.5 trillion (PROS SAY TAX HIKE REQUIRED)

The price tag for redemption has grown steadily for 15 years while an expanding country has focused on building new infrastructure rather than maintaining existing systems that were nearing the end of their natural life.

Since 2001, the cost of repairing those systems has mushroomed from $1.3 trillion to the current figure, more than three times as high, according to an assessment released Thursday by the American Society of Civil Engineers (ASCE). The report comes out every four years.

It gave the U.S. infrastructure an overall grade of D-plus, the same grade it received in 2013, "suggesting only incremental progress was made over the last four years."

"President Trump is on to something when he calls for a national rebuilding," ASCE President Norma Jean Mattei said in presenting the study. "But Congress and the American people have to pay for it."

She said lawmakers should raise the federal gas tax by 25 cents and index it to inflation.