Over the past few months, the Trump Administration has done an amazing job of completely upending the global status quo. Depending on your personal political point of view, that's either a really good thing or a really bad thing. Regardless, the impact on tourism is undeniable. The numbers of visitors from other countries to the United States is dropping dramatically. Current estimates are that the decline will cost the American economy billions of dollars and thousands of jobs.
As it turns out, Americans are concerned about traveling abroad, as well. Tourists from the United States play a major role in the economies in various countries, though Europe in general is a hot spot. But Americans are starting to rethink their travel plans. A big reason is the worldwide perception of their country until the current Trump regime, which isn't particularly positive in many places. Again, Europe is most certainly a hot bed of these sentiments.
While this isn't happening in large numbers, some potential American travelers are canceling trips due to worries about their reception in foreign countries. The current state of American politics is essentially amplifying issues that already existed. Many countries weren't fans of American tourists to begin with, seeing them as disruptive and rude. This obviously isn't every tourist from the United States but enough have caused problems that it's become the perception.
It's also worth noting this isn't the only concern American travelers are facing. The economy in the United States is in flux, leading to job losses and negative impacts on savings. Americans have less money to travel with, particularly to regions like Europe where costs have risen dramatically in recent years. There hasn't been a huge drop in American tourists traveling abroad, yet, but given the financial concerns and perception issues, many in the tourist industry know it's just a matter of time.