When it comes to where millionaires live in America, the rich keep getting richer.

Market research firm Phoenix Marketing International notes that although the total number of millionaire households rose for the 11th straight year in 2019, the gains were disproportionately seen in states that already had more than their fair share of millionaires.

"While the total number of high-net-worth households grew, these increases were largely seen in the wealthiest states, reinforcing the broader ongoing wealth-gap issues the country faces," says Carl Uttaro, VP of financial services research at Phoenix MI.

How Many Millionaires Are in the U.S.?

Phoenix MI is tracking the effects of the coronavirus pandemic, which could make for a very different landscape going forward. But last year, at least, the good times continued to roll. Indeed, a record 6.71% (or 8,386,508 out of 125,018,808 total U.S. households) can now claim millionaire status. That's up from 6.21% in 2018 and just 5.81% in 2017.

Note well that to be considered a millionaire by the standards of wealth research, a household must have investable assets of $1 million or more, excluding the value of real estate, employer-sponsored retirement plans and business partnerships, among other select assets.

Although California and New York have a great deal of millionaires in terms of raw numbers, they don't have the highest concentrations of rich households. It turns out there are numerous states with higher percentages of well-off households, several of which probably will surprise you.

And don't forget that between living costs and taxes, a million dollars goes much further in some states than others.

Here's a look at the millionaire rankings for all 50 states (plus the District of Columbia), based on the percentage of millionaire households in each. Just for good measure, we're also providing important tax and cost-of-living information.

Mississippi

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Mississippi consistently ranks as the state with the lowest concentration of millionaire households per capita in the U.S., but don't feel bad for the Magnolia State.

Thanks to low consumer prices and light taxes, Mississippi also is the second-least expensive state. Mississippi's cost of living stands at 14% below the national average, according to the U.S. Bureau of Economic Analysis. In an extreme example, Tupelo is one of the 10 cheapest cities in the U.S.

Mississippians also enjoy some of the lowest property taxes in the nation, and its income tax levy, already fairly low, continues to shrink.

That means everyone's paycheck, whether they're a millionaire or not, goes further than it does elsewhere.

West Virginia

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West Virginia has a relatively low concentration of millionaires, but the cost of living is 12.2% lower than the national average, according to the BEA.

West Virginia benefits from natural resources such as gas and coal, and it collects significant severance taxes from them. As such, the Mountain State's median real estate taxes are among the lowest in the U.S., according to the Tax Foundation. Sales taxes are reasonable, too.

But be forewarned: Income tax bites hard on higher incomes, with the top rate of 6.5% kicking in on taxable income over $60,000. Retirees will be happy to know that the tax on Social Security income is in the process of being phased out over a three-year period.

Arkansas

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Arkansas might not be bristling with millionaires, but it has the lowest living cost in the U.S., at 14.7% less than the national average. Heck, the cities of Jonesboro and Conway are among the least expensive places to live in the entire country.

And although median income is 24% below the national level, home prices are a whopping 42% cheaper than the U.S. median.

Arkansas is not tax-friendly. Property taxes are low in the Natural State, but sales taxes are tied with Tennessee for highest in the country. Even groceries are taxed (albeit at a lower rate). And income tax is particularly complicated in Arkansas.

Kentucky

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Kentucky has fewer than 84,000 millionaire households. But then, with a cost of living almost 12.2% below the national average, paychecks tend to go further. And median home prices are more than a third less expensive than the national level.

For those looking to attain millionaire status in Kentucky, the folks with the highest salaries are surgeons, anesthesiologists and obstetricians.

When it comes to paying taxes, the situation for Kentucky residents is mixed. The Bluegrass State recently moved to a 5% flat tax and opened up more items to its 6% sales tax. However, Social Security benefits are exempted from state income taxes, and property taxes are light.

Louisiana

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Louisiana's 90,000 millionaires, whose income depends on the state's economic staples, are likely to be feeling a pinch.

Tourism is under pressure from the coronavirus lockdown, while the petroleum industry