Changes in the top-of-the-atmosphere reflectance due to variations in the aerosol optical depth (τ) make retrieving τ from satellite possible. This aerosol signal is greatest for non-absorbing aerosol over dark surfaces and is least (often less than zero) for absorbing aerosols over bright surfaces. In general, previous aerosol retrieval research has been in regions where the signal is known to be large, for example, aerosol over ocean or biomass burning over heavily vegetated land. This study, however, looks at the aerosol signal and its variation over North America to determine when and where τ retrieval is possible. The results show that the aerosol signal is sufficiently large for τ retrieval over most of the sites studied; exceptions are located in the southwestern United States where the surface reflectance is large. Further, this aerosol signal closely corresponds with radiative transfer simulations, which suggests that aerosol optical depth retrieval over North America and the adjoining oceans is possible from geostationary orbit. The implication is that timely (e.g., 30 min intervals) observations of aerosol are possible. Such observations could aid research efforts in pollutant transport, air quality forecasting, and wildfire monitoring.