Help on Tax Rates - How to setup by ***Country*** (USA) instead of by State?

I’m trying to charge 6% Taxes (I am in the state of Pennsylvania) on all book orders placed by customers in the USA, however, I don’t see an option to do that.

Shopify instructions say “create a zone” in the Shipping section, then I can setup taxes for that zone. BUT, when I do that, it only allows me to setup taxes per state, when what I want to do is set up my tax rate per country (i.e., USA). How can I set up a tax rate of 6% for all customers by country instead of by state?

Thanks,

M