Burnham was born on May 11, 1861 on a Dakota Sioux Indian reservation in Minnesota, to a missionary family living near the small pioneer town of Tivoli (now gone), about 20 miles (32 km) from Mankato. His father, the Reverend Edwin Otway Burnham, was a Presbyterian minister educated and ordained in New York; he was born in Ghent, Kentucky. His mother Rebecca Russell Burnham had spent most of her childhood in Iowa, having emigrated with her family from Westminster, England at the age of three. In the Dakota War of 1862, Chief Little Crow and his Sioux warriors attacked the nearby town New Ulm, Minnesota; Burnham's father was in Mankato buying ammunition at the time, so when Burnham's mother saw Sioux approaching her cabin dressed in war paint, she knew she had to leave and could never escape carrying her baby.

Burnham returned to North America and for the next few years became associated with the Yaqui River irrigation project in Mexico. While investigating the Yaqui valley for mineral and agricultural resources, Burnham reasoned that a dam could provide year-round water to rich alluvial soil in the valley; turning the region into one of the garden spots of the world and generate much needed electricity. He purchased water rights and some 300 acres (1.2 km2) of land in this region and contacted an old friend from his time in Africa, John Hays Hammond, who conducted his own studies and then purchased an additional 900,000 acres (3,600 km2) of this land--an area the size of Rhode Island. Burnham together with Charles Frederick Holder made important archaeological discoveries of Mayan civilization in this region, including the Esperanza Stone. In 1909, William Howard Taft and Porfirio Diaz planned a summit in El Paso, Texas, and Ciudad Juarez, Mexico, an historic first meeting between a U.S. president and a Mexican president and also the first time an American president would cross the border into Mexico. But tensions rose on both sides of the border, including threats of assassination, so the Texas Rangers, 4,000 U.S. and Mexican troops, U.S. Secret Service agents, FBI agents and U.S. marshals were all called in to provide security. Burnham was put in charge of a 250 private security detail hired by Hammond, who in addition to owning large investments in Mexico was a close friend of Taft from Yale and a U.S. Vice-Presidential candidate in 1908. On October 16, the day of the summit, Burnham and Private C.R. Moore, a Texas Ranger, discovered a man holding a concealed palm pistol standing at the El Paso Chamber of Commerce building along the procession route. Burnham and Moore captured and disarmed the assassin within only a few feet of Taft and Diaz. After the Taft-Diaz summit, Burnham led a team of 500 men in guarding mining properties owned by Hammond, J. P. Morgan, and the Guggenheims in the Mexican state of Sonora. Just as the irrigation and mining projects were nearing completion in 1912, a long series of Mexican revolutions began. The final blow to these efforts came in 1917 when Mexico passed laws prohibiting the sale of land to foreigners. Burnham and Hammond carried their properties until 1930 and then sold them to the Mexican government. CANNOTANSWER

when did he get to mexico

Burnham returned to North America and for the next few years became associated with the Yaqui River irrigation project in Mexico.