While federal hiring has increased in recent years, federal workers, as a share of all Americans workers, remains at a historic low.

The civilian federal workforce, not including military personnel and postal workers, comprises about 2.4 million people. While a chunk of federal workers, about 20%, are in Washington, D.C., and the neighboring states of Maryland and Virginia, more than 80% are distributed outside the region.

Layoffs, targeted firings and the removal of independent officials are constrained by civil-service rules, federal laws and constitutional guarantees—all of which will face legal tests.