This world monthly surface station climatology has data for over 4700 different stations (2600 in more recent years). Data for some stations goes as far back as the mid-1700s. See decadal coverage for more detail. Most of the data was obtained directly from the National Climatic Data Center (NCDC), Asheville, North Carolina. However, much of the data prior to 1951 came from John Wolbach of Harvard College Observatory, who contracted to have this data key entered at NCDC. The first six months of 1961 were key entered at NCAR. Sharon Nicholson, Florida State University, provided African precipitation data to extend the records of over 250 stations. Dennis Shea, NCAR/CGD, has been a valuable source for data obtained directly from various countries.