States with some of the highest concentrations of graduate and professional degree holders tend to be located along the East Coast, according to a new analysis by the U.S. Census Bureau.

The survey, which looked at graduate-degree attainment for the 25-and-over population, found some of the highest levels of graduate and professional degrees in Massachusetts (14.5 percent), Maryland (14.1 percent), Connecticut (13.7 percent), Virginia (12.9 percent), New York (12.6 percent), and Vermont (12.3 percent). West of the Mississippi River, Colorado and New Mexico stood out with graduate degree rates of 11.5 percent and 11.0 percent, respectively. Graduate and professional degrees include master's, law, medical, and doctorate degrees.

The states with the lowest concentrations of graduate and professional degree holders include Mississippi (5.8 percent), Nevada (5.9 percent), South Dakota (6.1 percent), Iowa (6.3 percent), Arkansas and Oklahoma (both at 6.5 percent).

The nation's capital, the District of Columbia, counted 23.6 percent of its 25-and-over population with graduate degrees, more than any state. Nationwide, 9.4 percent of the population held graduate or professional degrees.

Among cities with populations of 250,000 or more, high rates of graduate degree attainment were found in Seattle (19.3 percent), San Francisco (18.5 percent), Atlanta (17.2 percent), Albuquerque, N.M. (16.6 percent), Boston (16.4 percent) and Austin, Texas (16.3 percent).

The findings are based on responses from a sample of 742,000 households.