diary-american-date-forms

diary-american-date-forms is a variable defined in `calendar.el'.
Its value is

((month "/" day "[^/0-9]")
 (month "/" day "/" year "[^0-9]")
 (monthname " *" day "[^,0-9]")
 (monthname " *" day ", *" year "[^0-9]")
 (dayname "\\W"))

• This variable may be risky if used as a file-local variable.

Documentation:
List of pseudo-patterns describing the American style of dates.
The defaults are: MONTH/DAY; MONTH/DAY/YEAR; MONTHNAME DAY;
MONTHNAME DAY, YEAR; DAYNAME. Normally you should not customize this,
but `diary-date-forms' (which see).

You can customize this variable.