Autocompleting place names as they are typed is a good way to guarantee accuracy. A user types in Ca and you suggest California. For auto completion to work well, design needs to account for a few things:
US states and Canadian provinces have two-letter abbreviations that should be accounted for. AR is the alpha code for Arkansas while also doubling up as the first two letters of Arizona. If a customer enters “AR” in the state field, they should receive autocomplete suggestions for both Arkansas and Arizona.
Common and official country names
Countries tend to have longer official names. For instance, Mexico is officially known as Estados Unidos Mexicanos (United Mexican States). There are times when an official name lacks the context which is given by the common name. The Koreas are a good example. South Korea calls itself the Republic of Korea while North Korea calls itself the Democratic People’s Republic of Korea.
Native language country names
The native language names of a number of countries tend to differ radically from the anglicized versions. Egyptians call their country Al-Misr while Germans call theirs Deutschland.
If a user types in the word “united” in the country selector, recommendations should be ranked based on popularity. That means the United Arab Emirates, despite having a higher alphabetical ranking, should come behind the United States and the United Kingdom.
City names should follow a similar pattern. Dallas, TX (pop 1.33million) should be recommended ahead of Dallas, GA (pop 13,000)
An address finder is preferable
This recommendation is if you don’t have an address finder (see best practice #123).