Alva B. Adams (October 29, 1875 - December 1, 1941) was a Coloradan and Democratic Party politician who represented Colorado in the United States Senate from 1923 until 1941.
Adams was born in Del Norte, Colorado and graduated from Phillips Academy in 1893, Yale University in 1896, and Columbia Law School in 1899. He became a county attorney in Pueblo County, Colorado in 1909, a regent of the State University of Colorado in 1911, and Pueblo city attorney in 1911.
During World War I, Adams served as a major in the Judge Advocate General's department in 1918 and 1919. In 1923, he was appointed to fill the vacancy in the United States Senate caused by the death of Samuel D. Nicholson. He served until a special election in November of 1924 (in which he did not run). He ran, but did not win, in the regular election in 1924 for Colorado's other U.S. Senate seat. He ran successfully in 1932 with Oscar L. Chapman managing his campaign, and again in 1938. He died in Washington, D.C. in 1941.
The Alva B. Adams tunnel, part of the Colorado-Big Thompson Project which passes under Rocky Mountain National Park is named for him.