The index ranges from zero to 100, with zero meaning no unity whatsoever, and 100 meaning complete unity. Most of the time, the country is somewhere between 50 and 70 or so.

Geer pointed to a 40-year graph his team put together, which showed the trend line peaking in the high 60s or low 70s in 1981, the first year measured, followed by a slow but obvious drop to its nadir during the Trump administration.

The data shows plenty of peaks and valleys in between, however.

The lowest point in the index came after the “Unite the Right” rally of white supremacist groups in Charlottesville, Va., which led to a backlash against President Donald Trump after he infamously defended the participants as including “some very fine people.”

High points included moments when Americans banded together amid geopolitical crises, including the Sept. 11, 2001, attacks and the first Gulf War in Iraq.