Editing Avondale, Arizona (section)

===Gila and Salt River Meridian===
[[File:Avondale-Gila and Salt River Meridan-2.jpg|thumb|{{center|The initial point of the Gila and Salt River Meridan}}]]
The surveying marker of the Gila and Salt River Meridian is located on Monument Hill. Ever since 1851, this has been the center point used by the state to measure the land in Arizona. The federal government recognized this point for measuring the boundary between the United States and Mexico after the [[Mexican–American War]] ended. The first survey, conducted in 1867, involved the first {{convert|36|mi}} of Arizona. Up until 1874, this was the epicenter of all surveying in Arizona for property deeds. It was listed in the [[National Register of Historic Places]] on October 15, 2002, Reference #02001137. Monument Hill is located at 115th Avenue and Baseline Road in Avondale.<ref>[http://kjzz.org/content/13073/did-you-know-monument-hill-important-arizona-spot Did You Know: Monument Hill Is an Important Arizona Spot]</ref>