São João da Fronteira (Portuguese meaning "Saint John of the frontier") is a municipality in the western part of the state of Piauí in Brazil.

The population is 6,064 (2020 est.)

in an area of 764.86 km².

[2] The elevation is 458 m. The municipality contains part of the 1,592,550 hectares (3,935,300 acres) Serra da Ibiapaba Environmental Protection Area, created in 1996.

[3] This Piauí, Brazil location article is a stub.