He married in 1958 to Gursharan Kaur. They have three daughters. PM's wife and youngest daughter Daman are accompanying him on this tour. Daman is a social worker and writer. In Pittsburgh their US-based daughter Amrit spent some time with the family.
Amrit Singh is a lawyer with the American Civil Liberties Union in New York City.
"On this occasion, I pray to God to give me strength so that I can serve my countrymen properly," he said.
When journalists expressed regret that they could not offer him a birthday cake on board Air India One, he said, "Your affection is enough for me."
Later, Dr Singh sent a cake to the media enclosure.
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