Cherigat won the men's race in 2:10.37 to beat countryman Robert Cheborer by 72 seconds. Kenyans won six of the first seven places among the men.
Ndereba, winning for the third time, finished in 2:23.27, just 16 seconds ahead of Elfenesh Alemu of Ethiopia. It was the closest finish ever in the women's race.
Kenya also won both races in 2002 (Rodgers Rop and Margaret Okaya) and 2000 (Elijah Lagat and Ndereba).
A Kenyan has won 14 of the past 17 men's races. Kenyan women have won four of the last five.
The top American finishers were Christopher Zieman, 13th at 2:25:45, and Mary Ann Protz, 15th at 2:57:58.
The last Boston Marathon winners from the United States were Gregory A. Meyer in 1983 and Lisa Larsen Weidenbach in 1985.
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