I was very happy to be notified today that a bug I reported to Zotero was fixed. Its list of OpenURL resolvers had a North America section, within which were all the United States libraries, plus some Canadian, and then more Canadian libraries were filed under Canada. This was not right. Now it’s fixed, and within North America there are two lists, for Canada and the United States.
I hope Mexico appears there soon—maybe a librarian there, or some Spanish-speaking librarian elsewhere, will send in a URL. And then maybe South America will follow.
This is what it looks like now (shown in operation on my demonstration Zotero account, coloured with a Solarized Light theme):

Many thanks, as always, to all the Zotero people for their work on this excellent program.