When C1CTYLKx is passed the city and state without a ZIP Code, C1CTYLKx attempts to return the ZIP Code for that city and state. C1CTYLKx can return a correct ZIP Code for a given city/state only if the city/state has a unique ZIP Code. Many cities are assigned more than one ZIP Code. When this is the case, C1CTYLKx returns the lowest ZIP Code in the range of the ZIP Codes for the input city/state and all ZIP Codes that the city/state fall within. This answer must be considered to be unreliable, as C1CTYLKx has no way to determine which ZIP Code is the correct one. When this is the case, the only reliable information returned is the short city name, long city name, and state abbreviation.