ABSTRACT Talke, S.A. and Jay, D.A., 2013. Nineteenth century North American and Pacific tidal data: lost or just forgotten? Tide data are the oldest and longest oceanographic records and comprise one of the few tools for understanding, quantifying, and separating century-scale human and climate impacts on the coastal zone. Our archival research indicates that continuous measurements of tides began in 1844 in the western Atlantic, 1853 in the Eastern Pacific, and 1858 in the Western Pacific. At least 50 multiyear tide series existed by the year 1900. With few exceptions, however, these 19th and early 20th century measurements have not been analyzed in more than a century and have been forgotten and neglected by the scientific community. This article describes historical tide measurements in the Pacific Ocean and North America, their current status, and ongoing efforts to recover the data. Possible uses of the data include assessing trends in sea level, tidal properties, and river flow, and reanalyzing extr...