Direct analysis in real time (DART) mass spectrometry has potential for rapid characterization of residues in and on archaeological materials, often without the need for extraction and sample preparation. These residues may provide insight into people’s behavior in the ancient past, including what they ate and drank and what plants they used. Residues change over time through oxidation, loss of water-soluble components during washing, and contamination from burial and handling. We are investigating how nicotine residues in historic smoking pipes from Historic St. Mary’s City, Maryland, have changed through time. To understand how residues change as they age and decompose, we are studying tobacco pipes that have been excavated and not cleaned, as well as pipes that have been cleaned and processed by the Historic St. Mary City museum. Nicotine and several of its oxidation products are readily observed in replica residues analyzed with DART-MS, even after the ceramic surfaces have been cleaned.