We have expected to decrease the number of tourism even internal tourist after U.S sanction but we have faced the rise in arrival of foreign tourist as well as internal tourism after sanction.
The rise in Rial makes these trips cheap for foreigners and more expensive for Iranian but Iranian themselves travel too much last year.
According to the Iranian Cultural Heritage, Handicrafts and Tourism Organization (ICHTO), there is a 50% increase in tourism during the last Iranian year 1397 (which is March 2018till March 2019)
The great number of tourists was Turkish, around 74% rise compared to the year before. Next increase of tourist was from Armenia, Azerbaijan, Russia, Iraq, and Oman.
The US sanctions decrease the value of Rial so foreigners find Iran as a budget destination.