In estimating the climate change impacts on coastal regions, critical questions such as how many people live within one kilometer or below three-meter elevation along the coast are often raised. Surprisingly, answers to these questions are not available in the literature. This type of fine-scale estimates of population along the coast is necessary to provide a realistic measure of the population most vulnerable to hurricanes and sea-level rise. This paper utilized four published datasets and geographic information system (GIS) methods to retrieve the answers for the 23 coastal states in the conterminous United States. The results show that about 19 million people reside within one kilometer from the shoreline in the conterminous U.S., whereas about 11.6 million people live below three-meter elevation. The state-by-state estimates reveal that Florida has the highest percentage of population living in areas below three meters (32.5%; 5.9 million people), followed by Louisiana (27.6%; 1.2 million people). The same methodology can be applied worldwide to estimate the most vulnerable coastal population to global climate change.