On September 22, 1820, the Mexico City Convention opened. The convention was sponsored by Andrew Jackson, the co-Governor of Jefferson and provisional president of Mexico, in order to create a union of the two (well, one-and-a-half) countries. In addition to Jefferson's legislature, the Chamber of Representatives, which had voted three months earlier to dissolve itself and reconvene in Mexico City, the convention's delegates included former Clericalists who supported Jackson, as well as non-voting delegates from the Indian tribes, and observers from the other Mexican factions.
On September 22, 1920, Mexican President Emiliano Calles joined John Walker, a slave who was due to be freed by Calles' Manumission Act, in confronting a mob. An anti-manumission group called the Sons of the Wilderness Walk had announced that if any freed slaves were processed through the Mexico City Manumission Bureau, it would be destroyed. A mob assembled in the plaza in front of the Bureau building on the morning of the 22nd, but before any slaves appeared, a government locomobile drove up, and Calles himself emerged. Calles passed silently through the jeering mob to enter the building. Rumors went through the mob that Calles would close the building, or that he would call out the army to disperse them. Instead, at 9:30 am, Calles emerged arm-in-arm with Walker, and accompanied him to the center of the jeering mob. The two men stood silently while the mob screamed for three minutes. After that, the screaming slowly died down, until the plaza was silent, and the mob began to disperse. By 10:00 am the plaza was empty except for Calles, Walker, and a group of twenty or so reporters.