It is important to note that states and counties are assigned these numeric codes based on an alphabetized list. Alabama being ‘01’ and Wyoming, ‘56’. Why you ask is Wyoming ‘56’ and not ‘50’? Did we add more six more states to the Union? Well, good question; ‘11’ is used to identify the District of Columbia, while the other five are reserved, but currently unused.
When published in 1970, the state codes were numbered 01-56, to leave space for inclusion of American Samoa (03), the Canal Zone (07), Guam (14), Puerto Rico (43), and the Virgin Islands (52). These places, along with other outlying areas, trust territories, freely associated states, and minor outlying island territories are currently identified with values from the range 60-80.
While the addition of a new state is uncommon, or unlikely, county names and boundaries do change occasionally. For this reason the lists of 3-digit county codes are adjusted when necessary, though still remaining alphabetized. Generally, counties are sequentially assigned codes in alphabetical order. However, codes are typically odd numbers, leaving some room for future adjustments and alterations.