On the two-decade anniversary of the U.S. invasion, Iraq is weakly governed, leaving it prone to instability and meddling by neighbors—especially Iran.

American politics turned hyper toxic several years ago, and ever since commentators have raised the specter of a second civil war. No other historical parallel, it seems, captures so viscerally today…

The most popular historical analogy for current American troubles is the Civil War era. The second most popular is the Gilded Age. But where the 1850s do not meaningfully resemble today, the 1890s ce…