Sulfate emissions from marine transport are an important part of the global sulfate emissions inventory. This study estimates long-term average sulfate deposition from marine transport in two general areas of the United States: the West Coast and the Great Lakes region. An analytical model of sulfate dispersion and reaction is used to predict combined wet and dry deposition rates. Emissions are roughly three times higher in the Great Lakes region than off the West Coast and result in substantially higher deposition rates from marine transport. In all locations studied, the contributions of marine transport to overall deposition rates were modest, in the range of 0.2 kg/ha-year to 2 kg/ha-year. Understanding the contribution from marine sources will help improve overall estimates of the sources of acid deposition and help focus regulatory attention on the most promising areas for reducing deposition rates in inland areas.