In an Access database you can easily get a list of the unique values in a column by running a SQL command.
This table contains multiple entries for many city names:
2. To get a deduped list go to Create . . . Query Design, and select 'SQL View' at the left of the toolbar.
3. Enter the following SQL command:
SELECT DISTINCT Olympics.City
The command SELECT DISTINCT picks a field in a table, and then FROM pulls that field from a designated table.
4. Click Run, and a new query will be generated listing each value in the table only once: