A hard-to-find monument on top of a hill in the Southwest Valley stands as a reminder that massive swaths of Arizona and the Southwest region of this country once belonged to Mexico. But it was all lost during the Mexican War, fought from 1846 to 1848.

The site, known as Monument Hill, is just east of the Phoenix International Raceway track in Avondale, at the top of a fairly easy hike that starts near Avondale Boulevard and Baseline Road.

A concrete "X" marks the spot on the hill where surveying began in 1851 by Andrew B. Gray and Lt. A. W. Whipple, American surveyors. The land survey was part of the deal struck with the Treaty of Guadalupe Hidalgo, signed in 1848, to resolve disputes over the new U.S.-Mexico boundaries.

With much debate over ownership of the land, the U.S. government ended up purchasing about 32,000 square miles of land from Mexico as part of the Gadsden Purchase. The Estrella Mountains that run through Goodyear, once part of Mexico, were enveloped into American soil and later became Maricopa County's first regional park.

From Avondale, a book by Jerry Squire and the City of Avondale: "The job was finished after much government red tape, Native American uprisings, long bouts of boredom because of the terrains and weather conditions, and even episodes of drunkenness. It is rumored that the crew became weary and wanted to return home so they cut the survey short, and Arizona never got its ocean port off the Sea of Cortez."

There were more complicated political decisions that ultimately denied Arizona beachfront property, but we won't bore you with those. Drunk and weary surveyors make for a much better story.

While the original monument was built on the initial point in 1851, the giant "X" was dedicated in April 1984. A press release announcing that ceremony noted that "a low, inconspicuous knoll 15 miles southwest of Phoenix takes on celebrity status . . . as the most important hill in Arizona."