A bundle of useful info from this – The Pocket Guide to Transportation – from the U.S. Department of Transportation.

Like what governments spend on highways and transit:

Transport Expend

.

And what revenues they get from highways and transit:

Transport Revenues

.

Let the interpretations begin.  (Like expenditures going up for highways, revenues going down.  For transit, both going up.)  And look at how the feds cut transit expenditures in 2007.

UPDATE: Eric Doherty provides a comparative link for Canadian spending on transit –

federal_transit_spending_graph