During the American Civil War, Cook was a correspondent in Washington, D.C., and with the Army of the Potomac for the Philadelphia Press.

He was on the editorial staff of the Philadelphia Public Ledger from 1865 to 1882, and the financial editor from 1883 to 1907.

He also served as president of the board of trade and of the Vessel Owners and Captains’ Association and as member of the Union League of Philadelphia.

[4] He was elected to Congress as a Republican to fill the vacancy caused by the resignation of John E. Reyburn.

He was reelected to the 61st United States Congress and served from 1907 until his death in Philadelphia.