Donald Trump in the White House has foreign tourists saying, "Thanks, but no thanks," on travel to the United States.

International tourism in the U.S. is down by as much as 16% since October 2016, according to a new analysis from Foursquare. While the data doesn't pinpoint the exact cause of the decline, there is little doubt the president's rhetoric on immigration and controversial travel ban are at least partially to blame. And the dip in travel to the U.S. could have big implications for a number of U.S. industries and the economy at large.

Foursquare looked at America's market share of international travel -- as in, the U.S. as a destination versus the rest of the world. It analyzed foot traffic trails on more than 50 million global users in over 150 countries.

It found that the U.S.'s market share of international travel fell by 6% year-over-year in October and continued to decrease through March 2016, when it dropped by 16% year-over-year. Currently, there is no sign of recovery in the data.

"The U.S. is losing tourist activity to foreign destinations," said Foursquare CEO Jeff Glueck in a blog post announcing the analysis.

Currency exchange rates could be partially to blame for the decline in international travel to the United States. The dollar has strengthened in recent months, and the euro is down, which could make European travel more attractive. But that's not the entire story.

Residents of the Middle East and Central and South America are avoiding the United States more than people from Asia, Europe or elsewhere. Both regions have been targeted by Trump.

The president regularly railed against Mexico on the campaign trail, and his administration has taken a tough stance on immigration. Trump has signed two executive orders attempting to ban travel from several Muslim-majority countries, which are currently tied up in the courts.

"International travelers may have determined that the America within their sights was less appealing or welcoming," Glueck said.

Foursquare isn't the first to suggest having Trump in the White House could harm America's travel business. Data released in February by travel search engine Kayak revealed steep declines in flight searches to popular U.S. destinations, and research from flight search app Hopper showed similar drops.

A fall-off in international tourism could have damaging effects to the already-struggling retail sector, travel, hospitality and the economy as a whole.

High-end retailer Tiffany , whose flagship store sits on the same block as Trump Tower, depends heavily on foreign shoppers and has seen its sales decline. The ongoing struggle of companies such as Macy's , Sears and J.C. Penney is well-documented.

Expedia EXPE CEO Dara Khosrowshahi told the Financial Times in a March interview that hotels and airlines in the U.S. are cutting prices as tourists avoid the country because of Trump's policies. "Either the U.S. has to go on sale in order to keep volumes up, or volumes are going to come down," he said.

Travel for business and leisure purposes supports 8.1% of America's GDP, said Rochelle Turner, research director at the World Travel & Tourism Council, and contributes over $1.5 trillion to the U.S. economy. The tourism and travel sector supports nearly 10% of jobs in the U.S., and visitor exports -- money spent by foreign visitors in a country -- generates about 10% of all exports from the U.S., including goods and services.

"A decrease in inbound travel into the U.S. can have a significant impact on the country's economy," Turner said. "Travel and tourism is a key generator of American jobs and economic growth."

Adam Sacks, the president of Tourism Economics, an international firm that forecasts travel trends, told the New York Times earlier this year that the annual number of foreign visitors in the United States could fall by 6.3 million between 2016 and 2018 because of reactions to Trump. The U.S. welcomed 77 million foreign visitors in 2016.

"We're going to be looking at a very challenging year for U.S. travel," he said.

Official monthly travel data from the National Travel and Tourism Office is currently updated only through August 2016.

Editors' pick: Originally published May 24.

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