«Though he soared deep into space and to the heights of Capitol Hill, his heart never strayed from his steadfast Ohio roots. Godspeed, John Glenn!» Ohio Governor John Kasich said in a statement.
After returning to Earth, Glenn was elected in 1974 as a Democrat to the US Senate, where he served for 25 years.
But he once again defied gravity, as well as age, in 1998 — 36 years after his historic flight — when he became the oldest man to travel to space at age 77.
The only son of a plumber and schoolteacher, Glenn was born in 1921 near New Concord, Ohio.
He married his childhood sweetheart, Annie Castor, and they had two children, David and Lyn.
Glenn became a combat pilot, serving in World War II and the Korean War before joining America’s space agency.
He earned six Distinguished Flying Crosses and flew more than 150 missions during the two conflicts.
After setting the transcontinental flight speed record as a test pilot, he joined Mercury 7, America’s first class of astronauts.
On 20 February 1962, he blasted off solo from a Cape Canaveral launch pad aboard a cramped capsule on an Atlas rocket to a new frontier for Americans.
He spent four hours, 55 minutes and 23 seconds in space, completing three laps around the world.
«Zero G (gravity) and I feel fine,» was Glenn’s remark on weightlessness. Seeing the Earth from 100 miles above, he famously quipped: «Oh, that view is tremendous!»
An operator in the Nasa control room told him: «You are very lucky.»
He replied: «You’re right. Man, this is beautiful.»
After splashdown in the Atlantic, Glenn was treated to a New York ticker-tape parade.
During his political career he was briefly considered as a running mate for Democratic presidential candidate Jimmy Carter.
But Glenn’s star dimmed after a meandering keynote address at the 1976 Democratic National Convention that led Mr Carter to call him «the most boring man I ever met».
He vied himself to be the party’s White House standard-bearer in 1984, but was beaten by Mr Carter’s Vice President, Walter Mondale.
In 2011, Glenn received the Congressional Gold Medal, the nation’s highest civilian award.
A year later, President Barack Obama presented him with the Presidential Medal of Freedom.
Paying tribute to the late astronaut, President Obama said in a statement on Thursday: «John spent his life breaking barriers, from defending our freedom as a decorated Marine Corps fighter pilot in World War II and Korea, to setting a transcontinental speed record, to becoming, at age 77, the oldest human to touch the stars.»
Also reacting to news of Glenn’s death, Nasa tweeted that he was «a true American hero».
«Godspeed, John Glenn. Ad astra», it added, with a Latin phrase that means, «to the stars».