Clay tobacco pipes are a unique form of artifact that has been recovered from the earliest colonial period sites to those of the early twentieth century. Archaeologists have found this artifact category useful for interpretive purposes due to their rapid technological and typological change, decoration, and maker's marks. Lack of adequate reporting in older site reports precludes a wide range of interpretive values intrinsic to this artifact category. A detailed study of tobacco pipe assemblages from the Pacific Northwest and Northern Plains, in an 1800 to 1890s time frame, demonstrates the interpretive value of this category on an intrasite, regional, and interregional basis. The detailed analysis given the pipes and pipe assemblages provides a historical background that encompasses the artifacts, the manufacturers, the sites, the relationships of the sites, and their place in the development of these regions. These tobacco pipes reflect the marketing and trade histories of these regions as well as many of the cultural subgroups.