https://en.wikipedia.org/wiki/North_American_Free_Trade_AgreementNafta wasn't entirely kept to even when it was in place (for example the us put a tariff on Canadian softwood lumber starting around 2000, citing subsidization, and Canada put a tariff on US milk saying that they were trying to dump excess product onto the Canadian market) but by and large you could trade with the US duty free in nearly every market. The economies of Canada, the United States, and Mexico were so intertwined that they were basically one economic block, similar to the EU. Prior to 9/11 you didn't even need a passport to enter the USA from other NAFTA countries.
Trump tore up that agreement, and made a new one in 2016. Now he's tearing up
that agreement and seemingly trying to decouple the USA from the economies of its closest partners. At least as far as things go in North America things have changed quite a lot. There's a lot more barriers to trade that didn't exist a few years ago, and it's much more expensive.
