Hanna is a town in Carbon County, Wyoming, United States. The population was 841 at the 2010 census. The town was started as a coal supply location for the Union Pacific Railroad. Much of the old town is built on top of the former workings of the Hanna No. 4 mine. On December 18, 1979, the Town of Hanna annexed the adjacent Town of Elmo. The population peaked at 2,288 in 1980 and has declined as local coal mines have ceased operation.
Hanna is located at 41°52′15″N 106°33′26″W (41.870928, -106.557297).
According to the United States Census Bureau, the town has a total area of 2.05 square miles (5.31 km2), all land.
As of the census of 2010, there were 841 people, 346 households, and 232 families living in the town. The population density was 410.2 inhabitants per square mile (158.4/km2). There were 497 housing units at an average density of 242.4 per square mile (93.6/km2). The racial makeup of the town was 95.6% White, 0.7% African American, 0.6% Native American, 1.2% from other races, and 1.9% from two or more races.