A Short History of the United States of Mexico (if we can figure out how)
The Mexican nation was born with the Constitution of 1824, which parallelled that of their neighbor to the north, the USA, with the exception of the establishment of the Roman Catholic Apostolic Church as the state religion.
Some historians still claim that members of the military were planning a coup in 1829, but this has never been conclusively established, and in any event the peaceful transition in the presidency set a precedent for future elections.
The next few decades saw the growth of the Mexican economy, though troubles still intermittantly cropped up from time to time. The Yucatan war led to the slaughter or expulsion to Guatemala of most of the Mayan population in that region in the 1840s. Trouble also occassionally cropped up with the Anglo settlers in the far north, who more often honored their pledges to convert to Catholicism in the breach rather than the keeping.
The late 1840s saw the discovery of the gold fields of Alta California, which greatly spurred development in the territory and led to the creation of new Mexican states in the region as the population grew. Some of this wealth went towards developing Mexican infrastructure, which had for several years lagged behind the Americans.
However, the movements of Mexican citizens into the North and American immigrants to the region from the East brought undesired attention to the Deseret community of the polygamistic Mormons, leading to their so-called 'Saints' War' against the United States of Mexico, which eventually resulted in their defeat and the expulsion of the Mormons to the Oregon Country north of the 42nd parallel, the Northernmost border of Mexico.
The 19th century saw increased immigration from Europe to both America and Mexico, drawn by the economic opportunities of the New World. A religious dicotomy developed in the immigration patterns of the two nations, with many Roman Catholics, especially Irish and Meditteranean nationalities, choosing the United States of Mexico, whereas Protestants, Eastern Orthodox, and Jews tended to be attracted to the purported religious freedoms of the United States of America.
The Isthmus of Tehuantepec was becoming a major transportation route between the gold fields of California and the rest of the world, and became one of the sites of major railway development for transoceanic shipments. However, a more ambitious vision for the Isthmus was the construction of a transoceanic canal. This vision would not be realized in full until the turn of the century, greatly assisted by the developments in steam diggers and explosives.
The Age of Expansion saw Mexico come into conflict with Spain over the Cuban revolution, and the Spanish-Mexican war saw the defeat of the Old World by the New. Cuba and Puerto Rico opted for statehood in the United States of Mexico, whereas the Philippines remained stubborn in their insistence on independence and this eventually was granted.
Mexico along with the USA, Great Britain, and Japan became guarantors of the neutrality and extraterritorial priveledges of the nations in the Kingdom of Hawai'i.
By the early twentieth century, the gold and silver wealth of the nation had begun to peter out, but were replaced by the new wealth of black gold in the state of Coahuila and Texas.
Also, social changes had finally come to the United States of Mexico. For decades, the priviledged position of the Church had been enshrined in the Constitution, but more and more was being eroded and challenged in day to day life, especially by protestant immigrants in the north. Eventually, a constitutional amendment was passed citing the historical and cultural significance of the Church in Mexican life, but removing the Church's priviledges and established status, making Mexico a nation of religious freedoms.