Commas in Dates and Geographic Units Mini- Lesson #35 From the Writing Lab’s 101 Grammar Mini-Lessons Series

Use a comma to separate each item in a date from the rest of the sentence. On December 8, 1941, the U.S. and Britain declared war on Japan.

Use a comma to separate each item in a geographic unit from the rest of the sentence. The German blitz against London, England, resulted in widespread destruction.

If the date is used as an adjective, do not place a comma after the year. The December 7, 1941 bombing of Pearl Harbor is an event that will live in infamy.

Do not place a comma after the parts of a date when only two units (the month and day or the month and year) are used. June 6, 1944, is the day on which allied forces invaded France during World War II. June 6 is the day on which allied forces invaded France during World War II.

If only the month and year are used, the comma is often omitted. The Battle of Iwo Jima took place in February 1945.