The number of black immigrants in the United States has more than quadrupled since 1980, a new study has found, and that group is expected to make up an increasing share of the nation’s black population in the decades ahead.

The study, released Thursday by the Pew Research Center, found that 3.8 million black immigrants lived in the United States in 2013, and their share of the black population in the country “is projected to rise from 9 percent today to 16 percent by 2060,” said Mark Hugo Lopez, the director of Hispanic research at Pew and an author of the study along with Monica Anderson.

That differs from the Hispanic population, Mr. Lopez said, because the share of Hispanics in America who are immigrants is declining.

Part of the reasons for the growth has been a number of federal laws over the years that have eased restrictions on immigrants, particularly for nations that had been underrepresented.