In 1888, Richmond took part in a United States Geological Survey expedition to Montana. He became an ornithological clerk at the United States Department of Agriculture. After a collecting trip to Nicaragua he joined the staff of the United States National Museum in Washington, D.C. as a nightwatchman. He was promoted to Aid, followed by Assistant in the birds department. He became Associate Curator of Birds in 1894. Richmond then became Associate Curator in 1918. He moved up to Curator in 1929, but stepped back to stay as Associate Curator, so that Herbert Friedmann could become Curator.