1.000 Pesos

The Estado de Buenos Ayres was a breakaway state from the Argentine Confederation, governing itself independently between 1852 and 1861 following Justo José de Urquiza's defeat of Rosas at Caseros. This note circulated during that secession period, when Buenos Aires maintained its own treasury, customs revenues, and currency entirely separate from the Confederation's financial apparatus in Paraná.

PS#423 places this within the Pick Specialized catalog for Latin American issues — the "S" prefix itself a signal that the issuing authority was a provincial or quasi-governmental body rather than a recognized national bank. Cotton substrate was the practical choice given chronic humidity along the Río de la Plata, though surviving examples frequently show foxing consistent with subtropical storage conditions.