While the Statue of Liberty still stands in New York’s harbor welcoming newcomers to American shores, the Trump administration has made it clear that most immigrants are not welcome .

That could have long-term implications for the U.S. economy. According to a new study by New American Economy, immigrants and their children have founded 45% of the Fortune 500 companies in the United States, generating $6.1 trillion in annual revenue last year. While the organization is admittedly a pro-immigration group, the numbers are pretty convincing. In Illinois, the revenue brought in by immigrant-founded Fortune 500 companies was equal to 70% of the state’s GDP. In states like New York, Georgia, Pennsylvania, and tech-heavy Washington State, more than half of the revenue brought in by Fortune 500 companies came from companies founded by immigrants or their children.

Overall, the Fortune 500 companies founded by immigrants and their kids employ 13.5 million people in the U.S., and employ 11% more people than the average Fortune 500 company with a nonimmigrant founder, the study found. It’s not just big companies, either. Nearly 3.2 million immigrants run their own businesses, including small and medium operations, and immigrants are more likely to be entrepreneurs than their U.S.-born counterparts. According to the study, these new entrepreneurs play a crucial role in keeping the economy growing as “nearly all net job growth in the United States is attributed to new firms and startups.”

U.S. history is filled with stories of immigrants who have had a serious impact on the American economy, people like industrialist Andrew Carnegie. Each year, through the “Great Immigrants, Great Americans” program, his namesake organization honors other immigrants making a difference in their new home. In addition to business founders, there are CEOs, MacArthur Genius Grant recipients, cancer researchers, a World Food Prize-winning geneticist, and many more.

Cutting off the immigration pipeline could have a deleterious impact on the economy, since at least 57% of workers in Silicon Valley are not born in the U.S. While the Trump Administration frames his travel ban and immigration restrictions as a protective measure for the United States, there are many stories and studies like this one showing how such policies are actually harming the American economy now and undoubtedly will in the future.