The answer appears to lie in the fact that America's relationship to the world has always been contested terrain. From the Know Nothings, to the Ku Klux Klan, to Trump's nativist movement, the United States has always contained plenty of people hostile to foreigners and celebrating a mythical "Americanism". And there have also been plenty of people-- from the League of Universal Brotherhood, to the United Nations Association, to Citizens for Global Solutions-- who have argued that we're all in this together.
At present, the America Firsters are clearly in control of the U.S. government. But, of course, the future is never predictable. Indeed, it's quite possible that there will be a revival of the impetus to build a global community-- one that can address the world's problems and even, perhaps, overcome them.
That would be a great day for both America and the world.
Lawrence S. Wittner (https://www.lawrenceswittner.com/ ) is Professor of History Emeritus at SUNY/Albany and the author of Confronting the Bomb (Stanford University Press).(Note: You can view every article as one long page if you sign up as an Advocate Member, or higher).