[dragonwriter]

> The USA was the largest economy in the world by 1890, despite pursing a policy of isolationism for the entire century before that.

The US was never isolationist unless you ignore the existence of Native American Nations; it was brutally expansionist from day one. From the time of the Monroe Doctrine, US imperialism expanded even further, leaving the US “isolationist” in most of the 19th Century mainly only in regard to what happened outside the Western Hemisphere, and not even always there.

[rayiner]

"Isolationism" when discussing U.S. history, and as relevant here, generally refers to our reluctance to our avoidance of alliances with European countries. (Or, really, anyone. In this context, "isolationism" isn't inconsistent with "expansionist." It's more about unilateral versus multi-lateral.)