Non-Hispanic whites are a dwindling share of the U.S. population, with their numbers dropping in the Northeast and Midwest and growing only modestly in the South and West, the Census Bureau said Thursday.

Whites declined in 15 states, almost all in the industrial and farming states from Massachusetts to Pennsylvania, and from Kansas to Ohio. They also declined in California and three Southern states, including Maryland.

A Census Bureau analysis of the 2010 count showed that the number of non-Hispanic whites rose over the decade from 194.5 million to 197 million, but the 1.2 percent growth rate fell far short of the national increase of 9.7 percent. Non-Hispanic whites are now 64  percent of the population, down from 69 percent a decade ago.

The census also reported that the black population grew by 12 percent. African Americans now make up almost 13 percent of the population, a small increase over the decade. More than half, 57 percent, live in the South, up from 55 percent a decade ago. And six out of 10 blacks live in 10 states, including Virginia and Maryland.

The census analysis of the nation’s white and black population underscores the transformative nature of growth in the 21st century. The number of Hispanics and Asians is soaring, the number of blacks is growing slowly and whites are almost at a standstill.

Hispanics are an ethnic group of people who can be of any race. Most Hispanics identified themselves as white. The number of whites who indicated for the census that they are Hispanic increased by 56 percent.

Whites who are not Hispanic are getting older on average, and have low birthrates that, when coupled with the high birthrates of Hispanics and Asians, make whites a smaller share of the population with every census count.

Even when Hispanics are included, the percentage of whites in the total population still declined over the past decade, from 75 percent to 72 percent.

Whites increasingly are gravitating to the South and the West. The white population grew by 4 percent in the South and 3 percent in the West over the decade. But it dropped by more than 1 million people, or 3 percent, in the Northeast and by 300,000 people in the Midwest, less than 1 percent.

Some states experienced outsize growth in the white population. The number rose by 10 percent or more in Arizona, Hawaii, Idaho, Nevada, North Carolina, South Carolina, Utah and Wyoming. The District, which the census treats as a state for statistical purposes, had a 32 percent leap in whites.

The decade also witnessed a large increase in the number of people who identified themselves as multiracial.

Every state saw its multiple-race population jump by at least 8 percent, and some of the largest increases were in the South. The number of multiracial people more than doubled in the Carolinas and came close to doubling in Georgia and Delaware. Nine of the 10 states with the biggest increases were Southern states.

The number of people who said they were white and black more than doubled and was the most common combination.