As part of NCDC's Climate Database Modernization Program, early colonial meteorological records and journals from the 1700's and 1800’s have been scanned and indexed, and are available online to the research community. These documents include U.S. Signal Service and Army records from the 1800's and observations from other voluntary observers from the mid- to late 1800s, who were managed by the Smithsonian Institution and the U.S. Department of Agriculture. These station networks eventually evolved into the Weather Bureau's Cooperative Observer Network. Weather observations at these stations typically included precipitation and temperature, recorded 3 times a day, especially for the earlier periods, and later, daily maximum and minimum temperature. At some stations, observations were also taken of cloud cover, wind direction and movement, barometric pressure, and dry-and wet-bulb temperatures, from which relative humidity was calculated. At stations near rivers or other bodies of water, river gauge height or water temperature may also have been observed. Over 35 distinct data types have been identified for digitization of the daily observations. Approximately 160 stations (about 3 per state) have been selected for priority digitization, with more stations to be digitized as funding permits. The digitization process has begun, with quality assurance applied to the digitized data to ensure accurate conversion of the data to digital form, as well as internal consistency among the various data types digitized. Significant changes in instrumentation and observation practices occurred during the period covered by this data set. A comprehensive set of metadata is being developed to complement the data set, including digitized information about station location, observers, and instrumentation. When completed, this digitized data set will allow for extension of the analysis of daily climate variables back into the 1800s and will provide a link between the more recent instrument records and paleoclimate records.