At the University of California, Berkeley, “instruction in class meetings normally begins ten minutes after the official start time.” A class listed from 10:00 to 10:59 runs from 10:10 to 11:00. At MIT, classes begin five minutes after and end five minutes before the posted times.
Here the institution itself sets the real start, and everyone knows it.
Broadway Direct advises theatergoers to arrive at least 20 minutes before the start time on their ticket. “Some theatres will not seat latecomers at all.” Others “will wait for a suitable break in the performance” before latecomers are taken to their seats.
On May 19, 1962, at a birthday celebration for President John F. Kennedy, the actor Peter Lawford introduced Marilyn Monroe again and again, and each time no one came on stage. When she finally appeared, he introduced her as “the late Marilyn Monroe.” The joke played on her reputation for arriving late.
In 1993 Newsweek reported that aides said President Bill Clinton operated on “Clinton Standard Time.” Chief Justice William Rehnquist once had to wait 45 minutes. The press waited 50 minutes on the tarmac at Andrews Air Force Base.
His press secretary, Dee Dee Myers, explained: “Things come up, and he does have to deal with them.”
At NYU Langone’s family health centers, a dental patient who arrives more than 15 minutes after the appointment time “will be considered late.” The patient may have to schedule a new appointment for another day.
Patients also wait for their doctors. A 2015 report by Vitals found an average wait of 19 minutes and 16 seconds.
Students at many American colleges believe they may leave if the professor is more than 15 minutes late. In 2015 Michigan State University’s student paper reported that the university has no such guidelines. The University of Pittsburgh’s student paper reported the same.
At Cal State Fullerton in 2012, the chair of the Academic Senate described an older custom. Students had to wait a set time for a late professor, and the time was “dependent upon the rank of the professor.”
The courts of Minnesota tell people to arrive at the courtroom 30 minutes before their hearing. “Court is not an appointment that can be missed or rescheduled.” In a criminal case, a person who does not appear may face a warrant for arrest. In a civil case, the person will likely lose by default.
On the day of the SAT, the college admission test, test centers open at 7:45 a.m. and doors close at 8 a.m. “You can’t be admitted once testing has started.” A student who is late must register again and pay the standard fee again.
For American airlines, a flight counts as on time if it departs from the gate or arrives at the gate less than 15 minutes after its scheduled time. Large airlines file monthly on-time reports, and the government publishes the results.
Even the official clock allows a margin.
Before 1883, American towns set their clocks by the sun, and there were more than 100 different local times. In October 1883, railroad delegates meeting in Chicago adopted a system of standard time. It took effect on November 18, 1883, the Day of Two Noons. Congress made standard time law with the Standard Time Act of March 19, 1918.