It's about as long as a William Henry Harrison's Presidency
(a.k.a. William Henry Harrison, a.k.a. "Tippecanoe," a.k.a. "Old Tippecanoe") (1841)
Having caught pneumonia and pleurisy early in his term as President of the United States, William Henry Harrison died after 31.520 days minutes in office. Following his death, Congress approved a Presidential widow's pension for Harrison's wife, Anna Symmes, who received a year's worth of Harrison's presidential salary — $25,000 — and the right to free postage for the remainder of her life.
It's about three-fifths as long as The First US Continental Congress
In other words, 31.520 days is 0.62 times the length of The First US Continental Congress, and the length of The First US Continental Congress is 1.6 times that amount.(1774) (Philadelphia, Pennsylvania)
The First Continental Congress — which included such notable members as Samuel Adams, Thomas Paine, Patrick Henry, John Jay and George Washington — met from September 5th to October 26th, 1774 — a total of 1 month, 3 weeks. Of the thirteen original American colonies in existence at the time, only the Province of Georgia sent no delegates to the Congress.
It's about half as long as Columbus' voyage to America
In other words, 31.520 days is 0.5 times the length of Columbus' voyage to America, and the length of Columbus' voyage to America is 2 times that amount.(1492) (first voyage)
Attempting to find a western route to Asia, Christopher Columbus set sail on August 3rd, 1492 and landed in the Bahamas on October 12th — 70 days later. After one of Columbus' ships, the Santa Maria ran aground in present-day Haiti, he ordered that the timber be used to used to build a fort and settlement called La Navidad; it remains missing to archaeologists to this day.
It's about half as long as The Voyage of the Mayflower
In other words, 31.520 days is 0.48 times the length of The Voyage of the Mayflower, and the length of The Voyage of the Mayflower is 2.1 times that amount.(1620)
Having left Southampton, England on September 16th (new style), 1620, the Mayflower dropped anchor near Cape Cod, Massachusetts 66 days later on November 21st (new style), 1620. The voyagers had planned to travel in a convoy of two ships, but the smaller Speedwell was found to be leaking (evidently as a result of sabotage) and all passengers had to be moved to the Mayflower instead.
It's about two times as long as Boniface VI's reign
In other words, 31.520 days is 2.1 times the length of Boniface VI's reign, and the length of Boniface VI's reign is 0.48 times that amount.(AD 896)
The Church's enigmatic, shortest-reigning Pope, Boniface VI was pontiff for a period of fifteen days in AD 896 before dying under somewhat mysterious circumstances. His election was subsequently pronounced null by Pope John IX because Boniface had been previously defrocked while serving as a Roman priest.
It's about one-third as long as The First spaceflight (Sputnik)
In other words, 31.520 days is 0.34 times the length of The First spaceflight (Sputnik), and the length of The First spaceflight (Sputnik) is 2.9 times that amount.(a.k.a. Sputnik 1, a.k.a. Спутник-1, a.k.a. "Satellite-1", a.k.a. Простейший Спутник-1) (1957) (total time in orbit)
Launched from Kazakhstan in 1957, Sputnik was the first artificial satellite placed into orbit around Earth, where it remained for 92 days. During its voyage, it traveled about 70,000,000 km (43,495,983.46 mi), completing an orbit of the planet every 0.067 days.
It's about three-tenths as long as The Spanish-American War
In other words, 31.520 days is 0.289 times the length of The Spanish-American War, and the length of The Spanish-American War is 3.46 times that amount.(1898)
The War between Spain and the United States over the liberation of Cuba began on April 25th, 1898 and lasted until the signing of the Treaty of Paris on August 12th, 1898, 3 months, 2 weeks, and 4 days later. The Treaty gave the United States control of Cuba, the Philippines, Puerto Rico, and Guam.