The purpose of this study was to investigate how water levels have changed in the lower Columbia River Estuary after more than a century of anthropogenic modification and climate change. We found and recovered analog tidal records from the US National Archives and the National Oceanographic and Atmospheric Administration for Astoria, Oregon, from the years 1853-1876. We digitized these records using a computer-based, line-reading algorithm and the help of many Portland State students. We read through thousands of documents and letters to determine the relative height of measurements from 1853-1876 and the land. The historical measurements were then connected with the modern record at Tongue Point in Astoria, Oregon (1925-present). Additional measurements found in archives showed that the 1925-1960 Tongue Point record needed to be corrected by up to 5 cm. We also digitized nearby measurements from Youngs Bay and Fort Stevens at the coast. Put all together, these records show that: (1) Relative sea-level is rising more slowly in Astoria than the global average, in part due to the effect of plate tectonics but possibly also the redistribution of ocean water towards the western Pacific; (2) At the coast, relative sea level has been dropping over the last century, due to tectonic uplift; (3) River flow has decreased by roughly 50% in spring and early summer, but increased by more than 30% in winter, compared to the mid-19th century; (4) Tidal range has increased by ~5% in the last century, mostly due to channel dredging and estuarine infrastructure. The seasonal cycle of tides and sea-level has shifted due to altered river flow, with possible ecological implications. Details are found in the journal article, and examples of archival records are given in the electronic supplement.