Geocoding

Geocoding transforms human-readable addresses into machine-usable coordinates. A geocoding engine parses the input address, standardizes its components, and matches it against a reference database of known addresses with associated coordinates. Depending on the quality of the match, the result may be rooftop-level (precise building location), interpolated (an estimated position along a street segment), or centroid-level (the center of a ZIP code or city).

Major geocoding services include the U.S. Census Bureau's free geocoder, Google Maps Geocoding API, and commercial providers like Smarty (formerly SmartyStreets) and Precisely. Accuracy varies: commercial services typically achieve rooftop precision for 85-95% of U.S. addresses.

ZIP code centroids (the geographic center of a ZCTA polygon) are the most common fallback when a full address is not available. Most ZIP code databases include latitude and longitude fields representing this centroid.