- (idiomatic, US) To supervise a group of people, such as workers, and/or their actions, i.e. their work.
- But Rabbit feels as though he owns it all, showing up at the showroom day after day, riding herd on the paperwork and the payroll [...]. - Rabbit Is Rich by John Updike
- As the new editor, his job is to ride herd on the staff and check on the tone of the articles.
From the cowboy task of driving cattle while riding along with them.