If 11 million immigrants were rounded up and removed from the country, many of the jobs they do — including restaurant, hotel and low-end construction work — could go largely unfilled, economists say. That would create a large and immediate hit to gross domestic product growth and the effects would ripple out to companies that supply goods and services to all those businesses. There would also be 11 million fewer people consuming goods and services, further driving down economic activity.

And on trade, Trump has argued for imposing big tariffs on goods imported from Mexico, China and elsewhere. The problem with this, many economists say, is the tariffs would ultimately be paid by U.S. consumers in the form of higher prices and would not lead to any significant increase U.S. manufacturing.

“It’s a common mistake that people who don’t really understand economics make that this would somehow be a tariff on exporters,” said Mark J. Perry, a professor at the University of Michigan at Flint and a scholar at the conservative American Enterprise Institute. “It would be actually be a tax on American consumers. And more than half of U.S. imports come in as raw materials. And those cheap imports benefit American companies that hire American workers to finish the production process. Trump is really harkening back to the outdated mercantilist positions of hundreds of years ago.”