The research underscores the growing economic contribution of immigrants, said Daniel Griswold of the Cato Institute, a Washington-based libertarian think tank. "While all the focus has been on outsourcing to India, this shows how important the inflow of Indian human capital has been to the American economy," Griswold said.
Certain immigrant groups favor certain states, the research showed.
Indians entrepreneurs, for example, are concentrated in California and New Jersey, British in California and Georgia and Chinese and Taiwanese in California.
The study also looked at California's Silicon Valley and Research Triangle Park in North Carolina to examine the role of regional tech centers in engineering and technoloy growth.
Over half52.4 percentof Silicon Valley startups had one or more immigrants as a key founder, while California's average was 38.8 percent.
And in Research Triangle Park, 18.7 percent of startups had an immigrant founder. The rest of the state averaged 13.9 percent.
Advocates of increasing the H-1B visa quota said the Duke research bolsters their case. Skilled immigrants add value to the U.S. economy, said attorney Marcy Stras, head of the business immigration practice at the Washington-based law firm Baker Hostetler.
"I'm very happy that there's something the government can take note of that positively proves that," Stras said.
Critics of previous Duke engineering studies have asserted that the reports are primarily intended to boost political support for increasing H-1B visa quotas.