The case for free trade does not care about borders. It cares about consumption, which there will be more of if things can be produced most efficiently. Things can be produced most efficiently with maximum specialisation, which is likeliest with free trade. Domestic production can be consumed more easily than foreign production so it is more valued because transport costs are lower.

The border between San Francisco is as relevant as that between California and Nevada, or the US and Mexico.

There are certainly things where it’s good to have domestic production, vaccines for one. But the argument is grossly overused. The wool of angora goats is protected in the US as of military value.

Trading for what you need has worked out well for plenty of countries. Switzerland, Luxembourg, Costa Rica, Bahrain, Singapore, Hong Kong, my native Ireland.

Domestic production is overrated.