Per capita millionaire households (Source: Phoenix Global Wealth Monitor)

More than 6 million households in the United States have liquid assets worth more than $1 million, according to new estimates that show the greatest concentrations of wealth in the United States are along the Interstate 95 corridor.

Maryland has the highest percentage of millionaires in the nation, the report by Phoenix Marketing International found, while New Jersey and Connecticut come in second and third. In all three states, more than 7 percent of households have net worths north of seven figures.

Millionaire households per capita

(Darker shades of green indicate higher per capita millionaire households. Source: Phoenix Global Wealth Monitor)

Massachusetts, Virginia, New Hampshire, Delaware and the District of Columbia all fall within the top 10. Hawaii, where 7.18 percent of households hold more than $1 million in assets, and Alaska, where 6.75 percent of households qualify, are the only two states outside the Northeast to crack the top 10.

Those high-worth households control almost three-quarters of the liquid wealth in the United States, said David Thompson, who runs the Phoenix Global Wealth Monitor.

States in the South make up the bulk of the bottom of the list. Fewer than 4 percent of households in Tennessee, Kentucky, West Virginia, Arkansas and Mississippi are worth $1 million or more. Just 3.76 percent of households in Idaho held more than $1 million in assets.

The Global Wealth Monitor estimates the number of millionaires based on the Survey of Consumer Finance and Nielsen-Claritas data.