When geographic locations, such as a city/state or city/country, full dates that include the month, day and year or titles applied to a person’s name are included in your writing, you must use commas to set distinguish them from the rest of the sentence.
When referring to geographic locations that include the city and state or the city and country are used, you must use a comma to offset both. For example:
INCORRECT: The stadium is in Green Bay, Wisconsin and it is the home of the Packers.
CORRECT: The stadium in Arlington, Texas, is the home of the Dallas Cowboys and is the largest one in the entire NFL.
When an address includes the street address with a number, a comma only follows the full street
address. For example:
INCORRECT: She has lived at the address of 1450, Santana Avenue, Kansas City, Missouri.
CORRECT: His address is 15 Montezuma Drive, Phoenix, Arizona.
When writing dates that include the month, date and year, you must offset all three with a comma when written in the traditional format. For example:
INCORRECT: September 11, 2001 is a day that many Americans are unlikely to forget.
CORRECT: December 7, 1941, is the day on which Pearl Harbor was bombed.
Similarly, if the day of the week is included, a comma must offset the day as well.
INCORRECT: Tuesday September 11, 2001, marks a day that is not easily forgotten.
CORRECT: Sunday, December 7, 1941, is the day that marks the bombing of Pearl Harbor.
When the date is written in the format of the day of the month, the month and the year, a comma is not necessary. Likewise, when just the month and year are used, no comma is necessary. For example:
INCORRECT: September, 2011, is a month that is likely to stay in the minds of many Americans, much like 7 December, 1941.
CORRECT: December 1941 stayed fresh in the minds of Americans for many years, as 11 September 2011 is likely to do as well.
The full date formatted in such a manner (day, month, year) is required for certain uses, style guides and regional norms, but it is not normally used in regular writing for conventional English, as it sounds a bit formal. However, when it is used, it is important that you punctuate it correctly.
When you are writing about specific individuals, you are likely to run across titles that define something about the person at some point. Titles, such as the “Jr.” to notate that a son has the same name as his father or “MD” to designate someone as a doctor, are offset with commas in the middle of the sentence and are preceded with a comma at the end of it.
INCORRECT: Jon James Jr. is not the son of Jon James MD.
CORRECT: Jon James, Jr., is not the son of Jon James, MD.