Seattle is an arcology – essentially a high-tech walled city. Nothing enters or leaves the city without going through many layers of security, both mundane and arcane. Visitors to the city must undergo blood tests in addition to a number of invasive scans. Food, air, and water which enter the city are filtered and screened multiple times, as well. It’s all “sanitized for your protection.”
Guests (delivery folk, visiting dignitaries, businessmen, etc.) are all given prominent VISITOR badges, and locals tend to keep a safe distance from visitors.
A sizeable shanty town has grown up outside the city, made of up people who, for one reason or another, were denied access to Seattle.
Seattle is as secure as a modern city can be.