Spatial anomaly patterns of sea-level pressures over North America, the North Pacific, and eastern Asia in the 20th century can be statistically calibrated with spatial anomaly pattern of tree growth in semi-arid western North America. Growth anomalies prior to 1900 were substituted into the calibration equations to reconstruct past circulation features for the 18th and 19th centuries. The success of the reconstructions for the Arctic was tested against climatic data where possible and against the variations in growth of Arctic trees which respond to variations in climate. Ten different types of tree-growth anomaly pattern were identified in the Arctic between 1800 and 1939. Climatic conditions inferred from the growth anomalies of Arctic trees were compared to circulation anomalies over the Arctic as reconstructed from the arid-site trees to the south. Both of these sources of information were used to infer climatic conditions for the period 1800-1939. Tentative inferences are presented as to climatic conditions for each of five regions in Alaska and northwestern Canada in hope that they may be tested against other lines of evidence.