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Use cardinal, not ordinal, numbers for dates. Examples:

April 1, not April 1st; July 4, not July 4th.

Spell out days of the week. For months, spell out when used alone; abbreviate when used with a specific date. But don’t abbreviate these months with five letters or less: March, April, May, June, July. Use numerals for years (e.g., 2025).

Use no punctuation with just month and year or season and year, but use commas if using the day and month together. Examples:

  • May 2012; spring 2010
  • a June 5, 2012, deadline
  • Join us on Friday, April 28, for a reception.


Decades are either spelled out (lowercased) or expressed in numerals. Examples:

  • the nineties
  • the 1990s, the ’90s, the mid-1930s.

a.m.; p.m.

Lowercase, with periods and a space after the number. Use figures to designate time, using a.m. and p.m. If the time is on the hour, do not use :00. Examples:

  • 4:30 a.m.
  • 4 p.m.

a.m. or p.m. do not need to be repeated if a time span is morning only or afternoon only:

  • 9:30–11 a.m.
  • 1–4 p.m.

For noon and midnight, use noon and midnight without the number 12. Or use a.m. (midnight) or p.m. (noon):

  • Lunch is at noon. Lunch is at 12 p.m.
  • Applications must be submitted before midnight. Applications must be submitted before 12 a.m.

Spans of time

For times of day, use an en dash between start and finish times, with no spaces before and after the en dash. Example:

25th Annual Nursing Conference
Saturday, Nov. 23
10 a.m.–3:30 p.m.

Use the words “from” and “to” when span of time is conveyed within a sentence. Example:

This year’s Nursing Conference will run from 10 a.m. to 3:30 p.m. on Saturday, Nov. 23.