Re:Why American Phone, Cable and Internet Bills are so High
by nowarninglabel on Monday September 24, 2012 @10:10PM
(#4568154)
Sorry for not looping back earlier, it's from http://www.usgovernmentspending.com/united_states_total_spen... which is getting its data from a few sources but I think for the transportation piece you can look on page 125 here http://www.gpo.gov/fdsys/pkg/BUDGET-2012-BUD/pdf/BUDGET-2012... but may want to cross-reference with the other sources.
Wikipedia saith that, as of 2007, 93.5% of the Federal contribution to the Interstate Highway System was funded by gas and vehicle taxes.
http://en.wikipedia.org/wiki/Interstate_Highways#Financing
And it notes that 1/6th of gas taxes and other user fee-like financing mechanisms are diverted toward public transit.