The 2012 survey by the Chicago Council on Global Affairs found that only 40 percent of respondents say large numbers of immigrants are a "critical threat." Just over half, 53 percent, call "controlling and reducing illegal immigration" a major foreign policy goal for the United States.
Both numbers are the lowest since the council began polling on the subject in 1994.
Concern about immigration has dropped by more than any other issue in the poll in the past 18 years, by 32 percentage points on whether reducing illegal immigration is a major goal and 19 points on the critical threat question.
A plurality of respondents said legal immigration should remain at its current level. The council also said concern about immigration has fallen among Democrats and independents and stayed steady among Republicans.
Midwesterners were more likely to be concerned about immigration than residents of other regions.