Dre Smith scored 11 points for the Patriots (11-3, 4-0 Colonial Athletic Association), who have beaten the Tigers 13 straight times. George Mason has won three straight and nine of 10 overall.
Monroe was dominant inside early, scoring eight points as George Mason built an early 22-8 lead. The Tigers never got closer than 30-22 on Thornton's 3-pointer with 1:05 left in the first half.
Towson finished with a 37-32 edge in rebounds, but shot only 20-for-52 from the field and 4-for-18 from 3-point range.
The Patriots converted 17 Tiger turnovers into 20 points.