The SSA has released the 2008 report of SSI recipients by state and county. You can scroll down the list to find your state.
Maine and New Hampshire have almost the same population (1.3 million people). But New Hampshire has half the number of SSI recipients as Maine does. Vermont has a similar number of SSI recipients to New Hampshire, but only half of its population (about 621,000 people). So Vermont resembles Maine is terms of SSI recipients as a percentage of the state's population.
So why is the number so different in New Hampshire? I practice in both Maine and New Hampshire, and haven't noticed a difference in the rate at which these claims are granted in the two states.
Hat tip to Charles Hall of Social Security News for recently publishing a link to these statistics.