Genoa is an unincorporated community and census-designated place in Miller County, Arkansas, United States. It was first listed as a CDP in the 2020 census with a population of 972. It is located 6 to 12 miles east of Texarkana along Highway 196. Although unincorporated, Genoa has a post office, with the ZIP code of 71840 for a specific post office box. …Genoa is an unincorporated community and census-designated place in Miller County, Arkansas, United States. It was first listed as a CDP in the 2020 census with a population of 972. It is located 6 to 12 miles east of Texarkana along Highway 196. Although unincorporated, Genoa has a post office, with the ZIP code of 71840 for a specific post office box. Most of the community is served by ZIP code 71854. Genoa also has its own school district, Genoa Central School District.