The state of Maryland had the most millionaire households per capita in the U.S. in 2013, according to a new report by New York-based research firm Phoenix Marketing International.

The annual report, which is published and sold to wealth-management firms, finds that Maryland ranked number one for the third consecutive year--with 7.7 percent of households boasting more than $1 million in investible assets.

Business owners looking to market to areas with a wealthy customer base--or in search of deep-pocketed investors--may also want to consider New Jersey, Connecticut, and Hawaii. Those states, perennially near the top of the list since the firm's inaugural report in 2006, filled out the next three spots, respectively.

About 6.15 million U.S. households had more than $1 million in investible assets in 2013, up 53,000 from the previous year, the report found. Phoenix collects its information from the Census Bureau, the Federal Reserve, and Nielsen.

For those in search of the next hotbed of millionaires, North Dakota might be a good place to start. The state, which ranked 29th, jumped 14 spots from 2012, the largest leap on the list. Many North Dakotans have seen pay increases thanks to the state's booming energy industry, The Wall Street Journal reports. 

Also moving up the list of states with millionaire households in 2013 were Maine (up 11 spots to number 25) and Louisiana (up 10 spots to number 32). Nevada dropped 20 spots to number 39 and Arizona, Florida, Idaho, and Michigan all fell more than 10 places.

David Thompson, managing director at Phoenix, tells the Journal that the changes to the list are a sign of the uneven economic recovery throughout the country. On Wednesday, the National Association of Counties reported that by some metrics only half the counties in the U.S. have recovered from the recession.