States have been gaining marriage equality at the rate of one or two a week lately, but a few stubborn holdouts may remain a serious challenge.
There are currently 17 states with marriage bans still in effect, mostly concentrated around the plains, the Midwest, and the Southeast.
If you're a gay or lesbian couple, you can't get married in Montana, though that could change very soon. A Ninth Circuit decision overturned bans in neighboring states, and a federal judge has indicated that he'll be ready to rule on Montana's ban any day now. State attorneys could conceivably appeal that decision, but they're unlikely to get a friendly reception from the Ninth Circuit at this point.
Nebraska and the Dakotas have pending litigation as well, but those lawsuits are still fairly new. Decisions there may not be forthcoming for several months.
In the South, there's no marriage equality from Texas to Florida. Various lawsuits in those states are moving along, and the next decision may come sometime after January, when the Fifth Circuit is scheduled to hear cases in Louisiana and Texas. A marriage-equality case in Mississippi, brought by the Campaign for Southern Equality and DOMA-fighting lawyer Roberta Kaplan, may join them as well.
In the Sixth Circuit, a court just upheld bans in Ohio, Tennessee, Michigan, and Kentucky. That decision now heads to the U.S. Supreme Court, which could take up a case anytime over the next few months. Or the Supreme Court could decline to hear those cases altogether.
Ultimately, all these lawsuits depend on the justices of the Supreme Court. If they decline to wade into the marriage-equality debate, equality organizers will have to turn to voters and legislators to overturn their marriage bans through good old-fashioned politics.