A new report from the Fiscal Policy Institute is suggesting that the rapid influx of immigrants - documented and undocumentated - has made a significant contribution to the overall Gross Domestic Product.

The report found that in the 25 largest metropolitan areas - including Atlanta which has seen the largest growth in immigrants' share of the labor force - foreign-born workers account for 20 percent of the economic output and make up 20 percent of the population. Given that those communities account for more than half of the nation's GDP, as well as two-thirds of all immigrants, that's an astounding number.

One of the primary reasons their contribution is so profound is that immigrants typically are of working age, and they are employed across the economic spectrum. The report notes that while most immigrants do figure to be working in lower-wage services or blue-collar jobs, 24 percent of them work in managerial and professional occupations. Another 25 percent work in technical, sales and administrative support. In addition, 22 percent of all proprietor's income in those 25 metro areas came from immigrants.

The report shows that economic growth is directly tied to the explosion of immigrants, whether they are documented or not. Atlanta, for instance, saw both the biggest growth in immigrants' share of the labor force and the fastest growth in its overall economy. In Georgia, between six and nine percent of the state's labor force is estimated to be undocumented immigrants, which is above the national average.

This is the first report that provides an accurate picture of the impact of immigrants on local economies and, in turn, on the overall GDP.