This is meaningless without a denominator. How much has international tourism increased in those years? What percentage of international tourists visited the US before and after 2001?

So it wasn't so bad that the number of people visiting the US decreased, but it was bad enough that it didn't increase as quickly as other places?

Anyways, let's compare to more "welcoming" places. This shows the slope of the data, so it's pretty easy to compare the changes between countries.

https://ourworldindata.org/grapher/international-tourist-tri...

If you have data that shows otherwise, feel free to share it.