According to the Congressional Budget Office, the HTF has been facing a funding gap of $107 billion. The federal per-gallon tax rates of 18.4 cents for gasoline and 24.4 cents for diesel fuel have stayed the same since 1993 1. As a result, HTF is spending more money annually than it is taking in. The Trump administration has proposed a $1 trillion investment in improving the quality of the nation's roads and highways. However, there has been much debate about how to generate these funds. Three main ideas have surfaced: A public-private partnership plan in which $200 million of federal spending will spur $800 million in private investment by companies operating the roads and collecting road tolls. A gradual increase in the per-gallon fuel taxes over several years. Converting major portions of the interstate system into toll roads