Many of the entrepreneurs we idolize and praise for their innovation and business success — traits we herald as specifically American — were not born here.

Elon Musk, the founder of SpaceX, was born in South Africa. Garrett Camp, a co-founder of Uber, was born in Canada. Jyoti Bansal, the founder of AppDynamics, was born in India.

Immigrants are turbo-charging startup innovation in the U.S., according to a report by the National Foundation for American Policy, a nonpartisan think tank based in Arlington, Va.In fact, of the U.S. companies currently valued at $1 billion or more, more than half (44 out of 87) had at least one foreign-born founder. Collectively, these 44 privately held “unicorns” are valued at $168 billion.

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Altogether, immigrant founders with startups valued at or north of $1 billion hail from 20 different countries. With 14 entrepreneurs in this category, India leads the pack. Canada and the United Kingdom come in second, with eight founders each, and Israel comes in third with seven.

“Immigrants play a key role in creating new, fast-growing companies, as evidenced by the prevalence of foreign-born founders and key personnel in the nation’s leading privately-held companies,” said Stuart Anderson, the author of the study, executive director of the National Foundation for American Policy, in a statement released with the study.

Immigrants aren’t just founders, of course. Nearly three-quarters of the billion-dollar startups had at least one immigrant in a key management or product development position.

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Despite having launched startups collectively valued at half of Russia’s stock market, it’s still difficult for immigrant entrepreneurs to obtain legal work status. According to the report, there is no “reliable mechanism” through which someone born in another country can obtain a greencard by starting a company in the U.S. that creates jobs.

Several bills currently pending in Congress would expand access to visas for immigrants working in the startup sector.

For example, the EB-JOBS Act (H.R. 3370) would grant an entrepreneur a two-year provisional visa with the potential to obtain permanent resident status. To qualify for the visa, the entrepreneur must create at least 10 jobs (or seven jobs paying more than $100,000 annually) or receive a $500,000 venture capital investment (or $100,000 from a qualified seed accelerator). Meanwhile, the Startup Act (S. 181) would give temporary status to up to 50,000 individuals who earned a master’s or doctorate degree in a science, technology, engineering or mathematics field from a U.S. university.

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