Tacna is a census-designated place (CDP) and colonia[3] in Yuma County, Arizona, United States.

[4] A post office named Tacna was created following the building of the Southern Pacific Railroad in the 1870s, but did not last long.

At the time he sold the town in 1941, it contained a post office and a restaurant called Noah's Ark.

After the town's sale, the post office was relocated four miles east, and the original railroad siding was renamed to Noah.

[5] There is an apocryphal story that the name Tacna is derived from Tachnopolis, a Greek priest from California who is supposed to have settled amongst the native population.

According to the United States Census Bureau, the CDP has a total area of 1.9 square miles (4.9 km2), all land.