This module will find the distance between two North American postcodes.

Included is a sqlite database with all of the postcodes and their
lat and long.

Postcode files come from here: http://geocoder.ca/?freedata=1

Table schema for the sqlite table:

CREATE TABLE postcodes (
  postcode TEXT NOT NULL,
  st TEXT NOT NULL,
  lat REAL NOT NULL,
  lon REAL NOT NULL,
);

CREATE INDEX postcode_idx ON postcodes (postcode);