A photograph purportedly showing a sign warning hikers about the maximum capacity of a suspension bridge in Costa Rica (it can hold ten people, but only three Americans) has been circulating online for several years:
The original photograph was taken at the Monteverde Cloud Forest Reserve in Costa Rica, several pictures of which document that the actual signs displayed in conjunction with that location's Sky Walk attraction do not single out overweight Americans. For example, the photograph below was posted by blogger Camo Jack on the Uncommonly Sensible blog in 2008:
In 2012, the Costa Rica Star published several photographs from the Monteverde Cloud Forest Reserve, including one showing the sign in question:
The Sky Walk is one of the main tourist attractions to the Monteverde Cloud Forest. While it's true that the park's operators have strict capacity limits for their bridges, they address weight rather than nationality.