Vancouver May Get Its Own RTA
http://blogs.thenewstribune.com/politics/2009/04/20/vancouver_clark_county_would_get_its_own
Basically, Vancouver, WA could form their own taxing district to invest in transit and transportation. This could include new I-5 bridges across the Coulmbia and light rail.
As others have noted however, it is very easy to cross the river to Portland, OR, and not pay any sales tax…