This package contains a database of city, state, latitude, and longitude information for U.S. ZIP codes from the CivicSpace Database (August 2004) augmented by Daniel Coven's federalgovernmentzipcodes.us web site (updated January 22, 2012). Previous versions of this package (before 1.0) were based solely on the CivicSpace data, so an original version of the CivicSpace database is also included.
clean.zipcodes function now returns NAs for blank and whitespace-only inputs as well
Added clearer warning to data's documentation that no updates have been made since 2004's publication
Cleaned up several aspects of the documentation and added sample output to each example