Which of the following sentences is correctly punctuated?

1 - On March 21 1985, our community held its bicentennial.

2 - On March 21, 1985, our community held its bicentennial.

3 - On March 21, 1985 our community held its bicentennial.

4 - On March 21, 1985 our community, held its bicentennial.

The answer would be option 2, On March 21, 1985, our community held its bicentennial. In this situation, the first comma is needed when separating the month and day from the year. The second comma is needed in the continuation of the sentence.

2 - On March 21, 1985, our community held its bicentennial.

Remember that whenever the month and day are presented with the year immediately following, the year should have a comma before and after it. This is, of course, if the year appears in the middle of the sentence like the example above. If the year ends the sentence, then, you would just have the comma before year and end the sentence normally as in the following:

"Our community held its bicentennial on March 21, 1985."