There are more than 46,000 miles of interstate highway in the United States, and it takes billions of dollars per year to keep them safe and in good condition.

The Highway Trust Fund, which helps with those billions of dollars in repairs, is getting lower and lower leaving State and Federal governments scrambling for solutions to keep it funded.

"The trust fund runs out of money in the summer," says Sen. Barbara Boxer, D-Calif.

Secretary of Transportation for the Commonwealth of Virginia, Aubrey Layne, says, "Many states are stepping up or have stepped up but we can only do so much. We need the federal government to do its part."

President Obama last week announced a $302 billion transportation bill. In the bill, he opens the door for states to collect tolls on interstate highways to raise funding for repairs.

The Highway Trust Fund currently relies on the 18.4 percent gas tax that hasn't been raised since 1993.