This event lead me to do research on Portland's underground Shanghai Tunnels. I have heard of them, but never knew a whole lot about them. Below is a brief description of the history of the tunnels.
Wikepedia's article on The Shanghai Tunnels
The Shanghai Tunnels, less commonly known as the Portland Underground, are a group of passages running underneath Old Town/Chinatown down to the central downtown section of Portland, Oregon, United States. The tunnels connected the basements of many downtown hotels and bars, to the waterfront of the Willamette River. They were built to move goods from the ships docked on the Willamette to the basement storage areas.
According to popular legend, around the end of the 19th Century they were used to kidnap or "shanghai" unsuspecting laborers and sell them as slaves to waiting ships at the waterfront. By the highest estimations, 1500 people per year were shanghaied out of Portland through the tunnels. Victims were drugged or knocked out, taken through one of the trap doors (or deadfalls), and held in a prison cell while they waited to be shipped off. This earned Portland the reputation as the most dangerous port on the West Coast, if not the world, in the early 1900s, as well as the nicknames "Unheavenly City" and "Forbidden City." Later, during Prohibition, the tunnels were inhabited by bars that literally went underground to sell alcohol.
Historians have stated that although the tunnels exist and Shanghaiing was practiced in Portland, there is no evidence that the tunnels were used for Shanghaiing.
Today tours of the tunnels are available through the Cascade Geographic Society and Portland Walking Tours.

