I travel to the DC metro area a lot with my work, and both the district itself and Maryland's Montgomery County have a nickel-per-bag tax for plastic bags, though they're not outlawed as they apparently are in California.
I have to admit that the nickel thing really tweaks me, as I don't typically carry change anymore and I usually forget to specifically ask for a bag until after my credit card has already been run and I'm being handed an armload of stuff that would very conveniently fit into 1 or 2 bags. (If you ask beforehand, they'll add it to the amount charged on your card.) Then I'm stuck, inconvenienced, and ticked off.