Drought is an important climatological phenomenon which has significant socioeconomic and environmental impacts. Several drought indices have been developed to quantify drought, but all of them rely on meteorological observations taken at instrumented in situ weather stations. The instrumental record for drought monitoring in the U.S. extends back only about a hundred years, and the record is even shorter in other countries such as Canada and Mexico. Reliable drought information can be derived from paleoclimatic data such as tree-rings, thus enabling researchers and decision-makers to assess drought variability and impacts over a multi-century period. Part 1 of this paper describes the development of the reconstructed paleoclimatic Palmer drought index gridded dataset for North America from tree-ring data. Part 2 of this paper describes how the reconstructed paleoclimatic data base is blended with a 20th century instrumental-based Palmer drought index gridded dataset for operational drought monitoring applications across North America.