Observational evidence suggests that the leading mode of variability in North America's winter circulation has changed around the 1980s. Before 1980, the Pacific-North America (PNA) mode dominates but afterwards, the dipole mode became the leading pattern (see figure). This presentation provides an overview and updates about the consensus and debate concerning the source of dipole variability and its changing pattern, as well as the projected future. Warming in the west Pacific, North Pacific, the ENSO region, and even the Indian Ocean has been linked to the occurrence of drought-enhancing western ridge of the dipole, with differing patterns and temporal characteristics. Coupled models have shown a strengthening of the relationship between the dipole and the West Coast precipitation, with a projected increase in both drought and deluge magnitudes in California. Other factors such as mid-latitude internal atmospheric dynamics could power the dipole variation and contribute to its amplitude. Part of the debate may result from differing definitions of North America's circulation anomaly: While some studies focused on the western ridge alone (which responds to different sources of atmospheric variability), others were concerned with the adjacent wave trains with a greater spatial extent. Furthermore, the Arctic amplification could interact with the mid-latitude circulation and influence the dipole fluctuation and trend. Finally, a large body of research has shown evidence of remote teleconnections of tropical origin leading to stagnation of the midlatitude stationary waves. The effect of an anthropogenic climate warming on amplifying these tropical teleconnections and associated dipole variations warrants further investigation.