Harding named Hoover his secretary of commerce. Hoover served in that role from 1921 until 1928, under both Harding and his successor Calvin Coolidge. Hoover expanded the Commerce Department significantly, so much so that some dubbed him the “the secretary of commerce … and under-secretary of everything else.” Others called him “the grand marshal of economic policy at home as abroad.” His department regulated radio, air travel, the census, and housing. And he attempted to wrest control of various activities and aspects from other departments.

When coal miners went on strike, President Harding tabbed Hoover, not the secretary of labor, to handle the situation.