Begining with the 2013 issue by purchasing a digital edition you now have access to all versions of The Old Farmer's Almanac. Each edition has unique conversion tables for tides, sun rise/set, moon rise/set and other astronomical data based on different major cities.

• Canadian = Ottawa. 
• National = Boston, MA
• Southern = Atlanta, GA (Savannah for Tides)
• Western = San Francisco, CA

You can purchase the digital edition here.