As there is no yet solution offered by the Maps API and manually filling in coordinates is nobody’s business, here’s a gem of an alternative. Found this answer on the GIS website–absolute lifesaver (would’ve saved jurihandl a LOT of minutes drawing Calgary, above ;D):
You can get polygon coordinates in json for using with googlemaps
using openstreetmap. Go to http://nominatim.openstreetmap.org/. Search
a place like “San Francisco, CA”Click on “Details”
Look for OSM ID and copy it (control+c), example: 2018776
Paste the ID http://polygons.openstreetmap.fr/index.py and download
the JSON file
Source: GIS