Choose Browse Cities by State/Country (on the main window or the Cities menu) to add several places at once from a built-in list of cities.
The dialog has tabs:
Once a region is loaded, its cities appear in a checklist. Check any number of them (or use Select All / Deselect All), then choose Add Selected Cities to add them to your list. Cities already in your list are skipped, and the app reports how many were added.
Use the Sort control to order the loaded cities by:
Add Region to Favorites saves the currently loaded state or country so you can reload it quickly from the Favorites tab later; the button toggles to remove it again. Favorites are saved whether you close the dialog with OK or Cancel.