Table 1 National monuments in Mountain West region designated between 1991 and 2014.

Pompey’s Pillar National Monument, created in 2001, is excluded because it is only 51 acres. Craters of the Moon was created as a small site in 1962 but greatly expanded in 2000 and therefore is included. Visitor statistics are provided by BLM National Conservation Lands Division; Chimney Rock statistics are available in (40) and are for 2017; and NPS portions of Craters of the Moon are from annual visitation reports available from NPS Integrated Resource Management Applications (IRMA) Portal.

National monumentStateAgencyYear createdAcresVisits, 2018
Organ Mountains-Desert PeaksNew MexicoBLM2014496,330415,690
Rio Grande del NorteNew MexicoBLM2013242,555199,664
Chimney RockColoradoUSFS20124,72617,518
Prehistoric TrackwaysNew MexicoBLM20095,28012,023
Kasha-Katuwe Tent RocksNew MexicoBLM20014,148301,238
Sonoran DesertArizonaBLM2001486,14928,064
Upper Missouri River BreaksMontanaBLM2001377,34638,290
Craters of the MoonIdahoNPS, BLM2000661,287267,660
Vermillion CliffsArizonaBLM2000293,000196,841
Canyon of the AncientsColoradoBLM2000164,000130,113
Ironwood ForestArizonaBLM2000128,91732,580
Agua FriaArizonaBLM200071,10043,729
Grand Canyon-ParashantArizonaBLM20001,014,00037,827
Grand Staircase-EscalanteUtahBLM19961,700,0001,157,915