Rountree, who goes by the nickname "Red," said he robbed his first bank when he was about 80 because he wanted revenge against banks for sending him into a financial crisis.
Rountree was sentenced on Friday to 151 months in a federal prison, which he will serve at the Federal Medical Center in Fort Worth, Texas.
He appeared in court in a loose-fitting prison outfit and shackles on his ankles. He had a cane to help him walk. Rountree listened to the proceedings through headphones because he is hard of hearing.
Police said Rountree, who was not armed, handed two envelopes to a teller at a bank in Abilene, Texas. One envelope had the word "robbery" written in red ink. Rountree told the teller to stuff money into the other envelope, or else she would get hurt.
After asking Rountree twice if he was kidding, she put the money into the envelope and Rountree then made off in a 1996 Buick sedan, police said."