Is American democracy breaking? How would we know?

Americans concerned with the strength of their democracy would do well to look at lessons from around the world. One is a warning: It often erodes before it collapses. Another is hopeful: It has the potential for regrowth.

It’s December 2024. No one is entirely sure who will be sworn in as president of the United States in January.

In this hypothetical scenario, the Democrat appears to have won the national popular vote, and has narrow leads in several key battleground states. But the Republican candidate learned from former President...