The National Register identifies seven characteristics of integrity: location, design, setting, materials, workmanship, feeling, and association.

Some of these, such as integrity of location, are quite rigidly enforced: a building that is moved can rarely achieve National Register status. More leeway, however, is allowed in other areas. I mentioned before the example of the Munsingwear Building and its 1960s glass-block windows.

A more extreme example is the original terminal at the Minneapolis-St. Paul Airport. This two-story building, placed in service in 1930, subsequently received a third story and a series of other additions. Just after World War II, two hangars built in the 1920s were moved across the field and attached to the front of the terminal for "temporary" passenger and office space - and, of course, they are still there. Despite these changes, the building has been determined eligible for the National Register.

The changes, in fact, are an important reflection of the growth of the aviation industry in the 1930s and 1940s.

On the Seattle Empire Laundry Building, the pattern of fenestration is maintained, and almost all the original sash remains on the north side.

The original sash on the other facades featured double-stacked, horizontally pivoting windows in groups of three per opening.

Replacement sash on these facades echoes the vertical tripartite division of the original sash and, on the first and second floors, the four tiers of panes of the double-stacked pivoting windows.

As I mentioned above, even though most of the windows were filled with glass block, the Munsingwear Building was listed in the National Register, which has exacting standards for integrity.

The integrity of the Empire Laundry'Ss windows is far better, and other changes to the exterior of the building are minor. The interior, although more altered, still retains vestiges of its laundry days, such as the drying room area, stairs, once-hydraulic elevator - even traces of the old machinery (see photo above left).