Rural 6 : Those areas that are not unsettled wilderness or uninhabitable territory but are sparsely populated, with densities below 500 persons per square mile
NFPA 1143 Standard for Wildland Fire Management, 2009 ed. www.nfpa.org/~/media/ACA7F4C34BAC4496B62D10DA55385 F2A.pdf, (Std: for Wildland Fr Mgt - Amer) {384 NFC}