Immigration over the past seven years was the highest for any seven-year period in American history, bringing 10.3 million new immigrants, more than half of them without legal status, according to an analysis of census data released today by the Center for Immigration Studies in Washington.

One in eight people living in the United States is an immigrant, the survey found, for a total of 37.9 million people — the highest level since the 1920s.

The survey was conducted by Steven A. Camarota, director of research at the center, which advocates reduced immigration.