According to The World Bank, the United States raked in $220 billion off tourism alone in 2014. With President Donald Trump in the White House, however, that may quickly be changing.

Hopper, a digital travel app, crunched the numbers to reveal the interest in travel to the United States has dropped sharply since Trump took office in January.

The app’s methodology is simple. Hopper calculated a number of flight searches conducted two weeks before President Trump came aboard and the number of flight searches conducted two weeks afterward—making the period that was analyzed approximately Jan. 6 to Feb. 3. The app then broke down the data according to which airports were searched for and calculated the difference. During this same span of time, the Trump White House instituted its much-repudiated travel ban from seven Muslim-majority countries, setting off a firestorm of criticism around the globe.

The results show that interest in travel to the United States declined 17 percent over the course of the tracked period. Understandably, searches really took a dive on the Saturday after the travel ban (Jan. 28). The data is based on averaging billions of flight searches, reports Hopper.

The results could be troubling for many U.S. markets that rely heavily on tourism. The cities most affected by the downward trend are major metropolises like San Francisco, New York, Washington, D.C., Las Vegas, and Los Angeles. And as Quartz points out, tourism is calculated as an export, “so any reduction in tourists from overseas could also exacerbate the U.S.’s trade deficit.”

There is some good news, however. Travel searches from Moscow to the United States have increased by 88 percent during that same time period.