Practically all of the observations in the early part of the record fall under the Cooperative Observer Program (COOP) maintained since 1890... There are definitely some outliers and even some occasional reporting errors in the SERCC and/or NC Climate Office Data that I made note of and accounted for in some of these maps and the NCDC has already pre-screened a considerable amount of this data and removed snowfall from stations that were deemed "unreliable"... While some of the observations may not be nearly as reliable as in the latter portions of the record (where more stations become automated, which bring about their own inherent biases), this is the best data we currently have available up to this point in time... General trends, spatial patterns, identification of large-scale meteorological features, and a historical chronology of winter weather at specific locations can be reasonably estimated.