The organization National Association of Town Watch (NATW) is the national promoter of National Night Out. Their website has some good ideas about party activities, as well as NNO-specific merchandise that you can purchase if you choose. But registering at their national site does NOT register you with the City of Portland. Registering with the City of Portland is the way you will get visits from police and fire, and the other local benefits of registering as covered by "Why register your party for National Night Out?" If you want these local benefits, you'll need to register locally.
ONI Main: 503-823-4519
City/County Info: 503-823-4000
1221 SW 4th Ave, Suite 110, Portland, OR 97204