So named by none other than Mark Twain, it's a useful catch phrase for the last decades of the 19th century. I've tried to include some history that old Mark might not have been aware of. In reaction to some of the excesses of the gilded age, progressivism called for reform, and imperialism called for conquest. Some would argue that the United States didn't truly emerge from the depression until all that spending on the war.
Turmoil is always just around the corner, and the U.S. found it at home and abroad.