Jack Lean, Charles's brother, built the Post Office around 1920. The front-gabled, steeply pitched portion was the original section. Jack Lean was a dog musher, carrying the mail on the Iditarod Trail, and was also part owner of some roadhouses in Rainy Pass. When he settled in Cooper Landing, he worked as a trapper and guide and carried the winter mail to Kenai. In the late 1930s he opened a store at Cooper Landing, probably adding the gable-roofed portion perpendicular to the original at that time. That section now serves as the post office, with the mail room located in an incompatible addition to the rear. Both of the original sections are of horizontal logs. The first has saddle-notched corners and a gable roof that extends in front to cover the porch, with bracing in the gable. The second section is constructed of logs sawn flat on three sides and placed on a concrete foundation.