The most common mistake in writing dates is to leave out one of the enclosing commas, usually the second one, like this:
I wrote this blog entry on April 26, 2007 in the afternoon.
Here, for easy reference, are the two most acceptable styles of writing dates in the United States. If you are including the day of the month, the date is written thus:
I wrote this blog entry on April 26, 2007, in the afternoon.
If you are not including the day of the month, the form is:
I wrote this blog entry in April 2007 in the afternoon.
I searched through the most recent editions I had of the style manuals on my bookcase. In support of these two styles were newspaper style guides, scientific and medical style guides, and general style guides:
- The Associated Press Style Book, 39th edition
- The New York Times Manual of Style and Usage, revised and expanded edition
- AMA Manual of Style: A Guide for Authors and Editors, 10th edition
- The ACS Style Guide: A Manual for Authors and Editors, 2nd edition
- Scientific Style and Format: The CBE Manual for Authors, Editors, and Publishers, 6th edition
- Publication Manual of the American Psychological Association, 4th edition
- Words Into Type, 3rd edition
- The Chicago Manual of Style, 14th edition (However, the stylebook says that the University of Chicago Press prefers dates in the style "I wrote this blog entry on 26 April 2007 in the afternoon.")