Lankford was born in Wilmington, Delaware, and attended private schools in Baltimore, Maryland, and Alexandria, Virginia.

He was employed as a lawyer in private practice, and engaged in active management of tobacco and cattle farms.

During World War II, Lankford served in the United States Naval Reserve from 1942 to 1946.

After the war, he was a member of the Maryland House of Delegates from 1948 to 1954, and was an unsuccessful Democratic candidate for election to the U.S. Congress in 1952.

He served on the Maryland Legislative Council in 1953, and was a delegate to the Democratic National Convention of 1956 before being elected to the U.S. Congress in 1954.