Weather regimes (WRs), which are persistent and recurrent flow configurations, are valuable for understanding more about the dynamics and predictability of the large-scale mid-latitude atmosphere. The WR perspective also bridges large-scale dynamics and surface anomalies through their influence on surface weather, including precipitation and temperature, extreme events, and storm tracks. Long-term shifts in surface temperature and precipitation over North America have been recently identified and can be linked to the planetary and synoptic scales (e.g. stationary waves and Arctic amplification). Some of these aforementioned large-scale changes could also manifest in WR characteristics over time. Due to the persistent nature of WRs, analyzing long-term changes in WRs also aids in understanding how atmospheric predictability at the subseasonal-to-seasonal scale is changing. In this study, we use 500-hPa geopotential height anomalies from reanalysis to compute WRs and analyze the long-term trends in their occurrence and duration. We find statistically significant trends showing that the daily occurrence of the Pacific Trough and Greenland High WRs is increasing, in contrast to the decreasing daily occurrence of the Alaskan Ridge and West Coast High WRs; these trends are particularly apparent during specific seasons. We further show that these changes in daily occurrence are related to changes in event duration rather than event frequency. Finally, we also document long-term changes in transitions between WRs, as well as in their spatial characteristics and the associated composite precipitation and temperature anomalies. Quantifying the relative importance of anthropogenic forcing versus natural variability in these shifts remains a challenge, and future research will explore data from general circulation models to address this important question.