Here's a PDF map that is a guide to the average frost depth in the continental USA. Just a guide; local building departments would have the most accurate local info. Usually. Not always. Not everywhere. Like some of the NM counties. 

yep...55" on our up-north property.  Ouch!!!

0"to 5" here good deal

One of the shortcomings can be found in the northern part of NM. Our property lies between the 10 and 15 inch lines. But from the old time locals up at 8800 feet it is more likely to be 24 inches in an average year, deeper in colder than normal times.   But it is a handy little approximate reference when one does not have anything better.

35 - 40 inches for me but this winter sure is a wierd one.  I bet we arent at 4 inches yet