Northwestern Improvement Company Store, historic building in Roslyn, Washington

The Northwestern Improvement Company Store is a large brick building located at the corner of First and Pennsylvania Streets in Roslyn, standing since 1889. The structure displays practical commercial design from the early 20th century with a rectangular shape, thick brick walls, and large windows focused on durability rather than decoration.

Built in 1889 for the Northwestern Improvement Company, a subsidiary of the Northern Pacific Railroad that ran coal mines on the Roslyn–Cle Elum Ridge, the store was the largest and busiest of its three company stores at Cle Elum, Ronald and Roslyn. Purchases were deducted from miners' paychecks, and a lantern lit in the window signalled that work was available. After the mining operation shut down the building passed into private ownership; the Roslyn Downtown Association bought it from a developer in 2011.

Purchases at the store were deducted from miners' paychecks, and a lantern lit in the window signalled that work was available. One section housed cobbler services. A woman who grew up in the mining days recalled it as "the forerunner of today's malls all under one roof," with groceries, clothing, shoes, yard goods and furniture.

The building runs 284 feet along the street, with an 88-foot front and a 52-foot back, and its walls are 12 to 15 inches thick. A metal railing separates the raised sidewalk and original facade from the street. The Roslyn Miners' Memorial stands in front, and its time capsule is set to be opened in 2046.

The building's windows retain most of their original cast iron shutters, fitted for security and fire protection. In the 1990s the store stood in for KBHR, the radio station of the fictional town of Cicely, Alaska, in the TV series Northern Exposure.