The Chesapeake & Ohio Railway began operating Mikados in December 1911, when it took delivery of the class K-1 from Alco-Richmond. Ten years later, the C&O purchased another 150 technologically superior 2-8-2's - the K-2's, the K-3's, and the K-3a's. All the K-2s and K-3s were built by Alco-Richmond. The primary thing differentiating the K-2s and K-3s was the booster. The K-2s had a booster, and although considered a "light Mikado", they could extert 10% more tractive effort than the booster-less K-3s. The C&O used its Mikados for almost any job, and they were considered the mainstay of C&O power for twenty years. They could be found on manifest freights, local freights, coal trains, work trains, and occasionally passenger trains. They were the dominant power on C&O's James River Line and also the Chicago Line in Indiana.
