A bill moving through Congress could help struggling transit systems around the country.

The Senate approved the Marketplace Fairness Act on Monday, a bill that would impose sales taxes on most items sold online to residents of the 45 states (and the District of Columbia) where stores charge sales tax.

PubliCola at SeattleMet highlighted the benefit to public transportation: “Local transit agencies rely heavily on sales taxes — in King County, for example, sales taxes contribute 54 percent of Metro funding — so a larger sales tax base translates into more funding for transit infrastructure.”

In fact, it could mean an additional $45.4 million each for Seattle’s metro and Sound Transit between 2014 and 2017. “For cash-strapped systems like Metro, that windfall could mean the difference between systemwide cuts and the first new service in years,” according to the SeattleMet article.

Seattle’s not the only city that stands to see a windfall for transit. More than a dozen other cities fund their public transportation systems using sales taxes, including Boston, Dallas, and San Francisco [PDF].

The Senate’s filibuster-proof 69-27 majority vote was a good sign, but the House is more divided on the bill. It’s not clear when the House will bring the measure up for a vote.