"The relationship between the peoples of the United States and Canada is excellent."

Translation: La rilato inter la popoloj de Usono kaj Kanado estas bonega.

[DiegoDiegoM]

I will say it

Peoples

[mikewhcheung]

This make me think: English evolved to use 'people' as a plural of 'person', but nowadays I barely hear someone say 'persons' except in a specific case. Are we supposed to distinguish 'people' from 'persons'?

[lingvulo]

You're right that persons is barely used, and generally only in techincal jargon. The normal plural of person is people, and you should basically always use it.

But there's also a singular word people, which is the one being used here. It refers to a large group of people with some sort of national or ethnic ties, and is popolo in Esperanto. Since this particular word people is singular, you can add an -s to make it plural, which is why it's peoples in this example.