So I was thinking; treaty ports in China were there to provide 'gateways' for European powers to Chinese markets, right? Or at least, that's what I think. I've never really been sure.
That said, could the concept have been applied to other nations? Britain had a lot of economic interest in South America during the 19th Century, for example; could they have taken port cities in Brazil or Argentina, Peru or Chile, to use as naval bases and economic gateways like they did in Hong Kong and other parts of China?
Edit: Of course, there is the Monroe Doctrine to contend with, but the US wasn't exactly Britain's equal in the 19th Century, and Britain's support of the Monroe Doctrine was purely in their own economic interest. On the back of that, would it make economic sense to have 'treaty ports' in the Americas?