When Donald Trump is greeted with a crescendo of“Namastes” when he lands in Ahmedabad he will be the seventh US president to visit India while in office.

President Dwight Eisenhower, a Republican, who came to India in 1959 at the height of the Cold War was the first to visit India as it was coming into its own as an independent nation and the laboratory of democracy.

The visits reflect in some ways the status of India in the US world view.

Eisenhower's visit was to explore India as a young democracy with hopes of closer cooperation, perhaps moving away from Prime Minister Jawaharlal Nehru's nonalignment.

While there have been gaps of about a decade between some of the visits, since Bill Clinton in 2000 every president has come to India in a sign of its rising importance in world efforts.

There was a ten-year gap between Eisenhower's visit and the next.

Democrats John Kennedy and Lyndon Johnson had skipped India that was firmly ensconced in the nonaligned movement. (Johnson, however, had visited Pakistan, then a US ally.)

President Richard Nixon, another, Republican, visited India in 1969 but his successor Gerald Ford did not.

Nine years later, Democrat Jimmy Carter made the India trip in 1978 while Moraji Desai of the Janata Party was prime minister.

His mother, Lillian Carter, had been a Peace Corps volunteer in Mumbai.

Ronald Reagan and George Bush (the senior) skipped India.

Democrat Bill Clinton came to India in 2000, ending the 12-year gap in presidential visits.

Since then, every president has come to India.

The highlight of Republican George W Bush's visit in 2006 was the signing of the landmark US-India Civil Nuclear Agreement – which was the only time a substantive agreement between the two countries was signed during a presidential visit.

The agreement, which he signed with Prime Minister Manmohan Singh, virtually recognises India as a nuclear weapons power exempting it from some of the US nuclear nonproliferation restrictions in order for both the countries to cooperate in the nuclear field with access to some civilian nuclear technology and materials.

It effectively neutralised some of the stringent sanctions imposed on India after its 1974 nuclear test.

Barack Obama, a Democrat, is the only president to have visited India twice.

He first visited India in 2010 when Singh was the prime minister.

Modi was the prime minister during his second visit in 2015 when he was the chief guest at India's Republic Day celebrations.