44th president turns 55: Photos of Obama through the years

President Obama turned 55 years old on Thursday, marking another milestone in the final year of his presidency.

With less than 100 days to go until Election Day, Obama is increasingly looking back at his tenure in office ? and his life. Last month, he went off on a tangent about his daughters, for example, remarking about how he's been "seeing them grow up and graduate from high school, and … now about to leave their dad." (Colin Campbell/Yahoo News)

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