How are candle lighting times determined from my zip code?

Since candle lighting times are determined from latitude and longitude, a process called geocoding is used to determine the geographic position of a zip code.

Our zip code database comes from the 1999 ZIP Code file from the U.S. Census Bureau’s Gazetteer project.

The Gazetteer data from 1999 is much more complete than their data from 1990 — but still not as good as the commercial-quality data you get from the U.S. Post Office. Gazetteer contains zip code, city name, latitude and lognitude but is missing time zone.

Fortunately, the Gazetteer data contain a FIPS code (which represents the county a zipcode is part of). The U.S. National Weather Service provides county-timezone data (keyed on FIPS code), which contains timezone and Daylight Saving Time data for each county. By joining these two data sources, we can get a complete picture of each zip code.