For Americans saving for retirement, Wyoming's loose tax code has helped propel it to the front of the pack.

Notably, residents don't pay state taxes on wages or capital gains. Both of these exemptions allow workers to save noticeably more of their earnings. What's more, even before the tax breaks, Wyoming residents have well-above-average incomes. For 2010, the state's average per capita income is estimated at $45,584. Only five states and the District of Columbia have higher incomes.

Wyoming's 6.8% unemployment rate is also well below the national average. Meanwhile, home prices there are expected to grow by 4.5% annually, on average, from 2010 to 2013, according to Moody's Analytics. Because many Americans sell their homes to downsize for retirement, price appreciation helps them grow their next eggs.

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