Mexico

Mexico — alternately, the United States of Mexico — was a nation in North America.

History
Circa the 15th century, the First Doctor, Susan, Ian Chesterton and Barbara Wright visited what would become Mexico. Barbara attempted (and failed) to alter the history of the Aztecs. (DW: The Aztecs)

In 1867, the War Lords kidnapped several soldiers from the Mexican Uprising for their War Games. (DW: The War Games)

In 1941, during the Day of the Dead, psychotic artist Susini attempted to create sculptures from the flesh and bone of living humans. Her plot was defeated by the Eighth Doctor and local artists Frida Kahlo and Diego Rivera. (DWM: The Way of All Flesh)

In 1994, the Seventh Doctor, Ace and Bernice Summerfield visited Mexico, meeting Cristián Xochitl Alvarez and investigating Huitzilin and the 'Blue'. (NA: The Left-Handed Hummingbird)

In the early 21st century, the United States fought a war with Mexico. (NA: Cat's Cradle: Warhead)

The Torchwood Institute was aware that a small time rift was present in Mexico. (TM: Shrouded) Following his encounter with Torchwood Three, Captain John Hart left to reside in Mexico. (TW: Exit Wounds)

Notable individuals' ties to Mexico

 * Mexico was the birthplace of attempted dictator Ramón Salamander. (DW: The Enemy of the World)
 * Former Time Agent John Hart based himself out of Mexico after moving to 21st century Earth. (TM: Shrouded)

Other references

 * The Sixth Doctor promised Evelyn Smythe that he would go to Mexico or Havana to pick up some specialty chocolate for her to use if she agreed to travel with him. (BFA: The Marian Conspiracy)

Alternate realities

 * In the alternate reality of Pete's World, Mexico extended up to Arizona - implying its victory in a second Mexican-American War - and possessed a Prime Minister. It was referred to by its full name, United States of Mexico, rather than just Mexico. (WEB: Cybus Industries website)