From March 1933 to April 1934, he was the longest-serving current member of Congress and was the Dean of the United States House of Representatives.

After practicing law in Smithfield, North Carolina for a number of years, he served as a Democratic U.S. Representative from North Carolina's 4th district, 1901–1934, and served as chairman of the Committee on Claims (abolished in 1946) and then of the House Rules Committee.

Pou is notable for his support of Louis F. Post, United States Secretary of Labor and head of the Bureau of Immigration, who had, in the era of the Palmer Raids, reversed many of the decisions of the Attorney General and his aide J. Edgar Hoover as to deportations.

On April 15, 1920, Kansas Congressman Homer Hoch accused Post of having abused his power and called for his impeachment.

In a dramatic exchange, Congressman Pou, a Democratic supporter of the anti-radical campaign, praised Post's actions, saying, "I believe you have followed your sense of duty absolutely," and walked out of the room, leaving it in stunned silence.