The growth since 1970 in the numbers of immigrants living in the U.S. is far out-pacing the growth of native-born Americans, according to a new study of census data.

According to the Center for Immigration Studies, in a report based on Census Bureau data:

• Immigrants now account for nearly one in 10 U.S. residents, the highest proportion in seven decades -- compared to just under one in 20 in 1970.

• With 27 percent coming from Mexico, California, New York and Florida have been heavily impacted.

• The new immigrants are poorer, less educated and inclined to wind up on welfare.

During the 1930s, about 14.3 million immigrants were living in the U.S. The number fell to a decade low of 9.6 million in the 1970s. By 1998, the number had risen to 26.3 million.

Source: Gabriel Escobar, "Immigrants' Ranks Tripled in 29 Years," Washington Post, January 9, 1999.