Like many cities, Tacoma has gone through periods of growth and decline, during which there have been various attempts to tear down much of the historic fabric of the city. When times are tough, demolition is touted as a way to revitalize an area, leading to such mistakes as the parking garages on Pacific Avenue, which were hoped to keep shoppers and businesses in the downtown after Tacoma Mall opened. Numerous historic buildings were raised to construct these garages, which created pedestrian "dead zones" that the city is trying to rehabilitate--or tear down in turn.
When times are good, old buildings often stand in the way of major projects, and developers want to see older structures levelled in order to gain access to the land.
Fortunately, Tacoma has been able to preserve a good chunk of its historical buildings, and has experienced a real transformation of formerly derelict stock. UW Tacoma is forged from a number of previously abandoned industrial structures downtown, the old Union Station is now a federal courthouse, Albers Mill next to the Museum of Glass are apartments.
And now Historic Tacoma has come into being--a citizen organization dedicated to preserving the city's architecture. This is a positive development, as it means the city's Landmark Preservation Commission (which I served on for four years) will have a civic partner.
If you're interested in historic preservation or what's up with these issues in Tacoma, check out their site.