What country do Americans most often visit?
When I was young, I noticed American tourist tours of the type "15 European capitals in 15 days"!
Maybe now is different.
The higher valued dollar has helped promote world travel for Americans. Record breaking numbers of US residents traveled abroad in 2014 and 2015. The winner of the most visited country by Americans for the last few years is Mexico, with a 24% increase (25.8 million).
A very distant second is Canada at 6.9 million and third most visited is the United Kingdom at 2.8 million. Rounding out the rest of the top five are Dominican Republic with 2.7 million and finally France at 2.1 million.
Canada and Mexico obviously benefit from proximity and being cheap for American dollars.
Outside of North America it's the UK, Dominican Republic, France, Italy and Germany for the Top 5.