US 4-Digit
Maidenhead Grid Squares

There are 488 grid squares in the contiguous 48 states. Each 2° by 1° area is about 100 by 70 miles.
Each major field "DN" contains 10x10 or 100 numbered grid squares, e.g. DN00 - DN99.
Each square is further divided by adding two letters, as in CN97xn, about 4 by 3 miles. Read the ARRL introduction. Image by Icom America.