Studies show that the elimination of barriers to migration would have profound effects on world GDP, with estimates of gains ranging between 67–147.3% in the scenarios where billions of workers move from developing to developed countries. Research also finds that migration leads to greater trade in goods and services, and increases in financial flows between the sending and receiving countries. Using 130 years of data on historical migrations to the United States, one study finds "that a doubling of the number of residents with ancestry from a given foreign country relative to the mean increases by 4.2 percentage points the probability that at least one local firm invests in that country, and increases by 31% the number of employees at domestic recipients of FDI from that country. The size of these effects increases with the ethnic diversity of the local population, the geographic distance to the origin country, and the ethno-linguistic fractionalization of the origin country." A 2017 study found that "immigrants' genetic diversity is significantly positively correlated with measures of U.S. counties' economic development the Age of Mass Migration. There exists also a significant positive relationship between immigrants' genetic diversity in 1870 and contemporaneous measures of U.S. counties' average income."