As the nation wrestles with what policing should look like in the 21st century, many question whether these smallest of police departments — which function in nearly every state, employ more than 20,000 officers nationwide and provide the first line of defense for millions of Americans — can adequately carry out their mission. Officials in some states have pushed to consolidate the smallest departments into larger, neighboring agencies, often triggering opposition.

“The only reason they exist is because of politics, and they provide jobs for some individuals,” said Charles A. McClelland Jr., who led the Houston Police Department from 2010 to 2016. “Uvalde is a perfect example of what’s wrong with the disjointed law enforcement jurisdictions we have in this country. Even though it happened in Texas, it can happen anywhere.”

Agencies with fewer than 10 officers make up nearly half the nation’s more than 12,200 local departments, a 2016 federal survey found. In many cases, these agencies have sprung up and evolved alongside the towns and communities they serve…

It’s difficult or impossible, however, for these departments to match the resources of bigger ones — resources that go into things like training, communications systems, body cameras and professional standards units.