Welcome. Hope you enjoy your stay before shipping out.
I made that map you mention - it was tricky to draw because the program I was using (Microsoft MapPoint 2009) doesn't care about city boundaries as much as it does about "census" areas, which apparently cities don't always use for their boundaries.
Here's a more detailed map of Portland, showing the exact boundaries. Portland has a no-loaded-open-carry ordinance (without CHL) and recent challenges indicates that "loaded" includes rounds in magazines anywhere on your person. Loose rounds are permitted.
City Boundary Map: http://www.portlandonline.com/shared...e.cfm?id=51672
Ordinance forbidding the carry of loaded firearms: http://www.portlandonline.com/Audito...14&a=15437
Oregon City has this neato interactive map Web Application at: http://maps.orcity.org/ that shows boundaries.
Hope this helps,
P.S. - See you tonight...