USA States And Cities in C# List

Here is a states dictionary:

public string stateAbbreviationExpand(string abbr)
{
Dictionary<string,> states = new Dictionary<string,>();

states.Add("AL", "Alabama");
states.Add("AK", "Alaska");
states.Add("AZ", "Arizona");
states.Add("AR", "Arkansas");
states.Add("CA", "California");
states.Add("CO", "Colorado");
states.Add("CT", "Connecticut");
states.Add("DE", "Delaware");
states.Add("DC", "District of Columbia");
states.Add("FL", "Florida");
states.Add("GA", "Georgia");
states.Add("HI", "Hawaii");
states.Add("ID", "Idaho");
states.Add("IL", "Illinois");
states.Add("IN", "Indiana");
states.Add("IA", "Iowa");
states.Add("KS", "Kansas");
states.Add("KY", "Kentucky");
states.Add("LA", "Louisiana");
states.Add("ME", "Maine");
states.Add("MD", "Maryland");
states.Add("MA", "Massachusetts");
states.Add("MI", "Michigan");
states.Add("MN", "Minnesota");
states.Add("MS", "Mississippi");
states.Add("MO", "Missouri");
states.Add("MT", "Montana");
states.Add("NE", "Nebraska");
states.Add("NV", "Nevada");
states.Add("NH", "New Hampshire");
states.Add("NJ", "New Jersey");
states.Add("NM", "New Mexico");
states.Add("NY", "New York");
states.Add("NC", "North Carolina");
states.Add("ND", "North Dakota");
states.Add("OH", "Ohio");
states.Add("OK", "Oklahoma");
states.Add("OR", "Oregon");
states.Add("PA", "Pennsylvania");
states.Add("RI", "Rhode Island");
states.Add("SC", "South Carolina");
states.Add("SD", "South Dakota");
states.Add("TN", "Tennessee");
states.Add("TX", "Texas");
states.Add("UT", "Utah");
states.Add("VT", "Vermont");
states.Add("VA", "Virginia");
states.Add("WA", "Washington");
states.Add("WV", "West Virginia");
states.Add("WI", "Wisconsin");
states.Add("WY", "Wyoming");
if (states.ContainsKey(abbr))
return (states[abbr]);
/* error handler is to return an empty string rather than throwing an exception */
return "";
}

You can add the cities in a dictionary tree likewise