Born in Bee,[Bee 1] West Virginia, Knapp received an Artium Baccalaureus degree from West Virginia University Institute of Technology in 1932, a Master of Arts from West Virginia University in 1934, and a Bachelor of Laws from West Virginia University College of Law in 1940.
He was an attorney for the United States War Department from 1942 to 1944.
He was a judge of the Court of Common Pleas for Kanawha County, West Virginia from 1957 to 1970.
[1] On December 8, 1970, Knapp was nominated by President Richard Nixon to a new seat on the United States District Court for the Southern District of West Virginia created by 84 Stat.
He assumed senior status on February 25, 1983, and served in that capacity until his death on December 25, 1998, in South Charleston, West Virginia.