I have a spreadsheet with 7500+ rows of data. In one of the columns, it lists cities, but they repeat many times. Is there a way to highlight that particular column and determine how many DIFFERENT cities there are in the 7500 rows of data.

The spreadsheet is already sorted by that column (city) and I guess I could scroll down and hand count it but I know there is an easier way to do it but I can't remember.

Any help would be appreciated because eventually there will be nine spreadsheets totalling 65,000 rows and I don't need all that information.