Wildlife management agencies in US states and Canadian provinces and territories routinely assess population trends of American black bears (Ursus americanus) and estimate population size. State or province-wide population estimates are often extrapolated from small, short-term studies or are based on other expert opinions. We compiled black bear population estimates provided by 51 states and provinces for the period 1988–2001. Only 57% of trends ascertained from these serial population estimates (or less, depending on the method for determining trend and what was considered a match) agreed with corresponding agency assessments of trend for the same period. That is, nearly half the management agencies felt that the trend in their bear population was different than indicated by the estimates they produced. Most mismatches were cases where agencies perceived their populations as increasing but their estimates showed no discernible trend. Pooling all population estimates for North America suggested that continent-wide black bear numbers had increased by about 2%/year, but this growth cannot be statistically corroborated because of the subjective nature of the individual estimates (guesstimates). State or province-wide black bear population estimates may aid in managing bear harvests, but for the most part, they are not precise or rigorous enough to provide useful information on population trend.