pl.wikipedia.org/wiki/Petr%C3%B3polis

This sentence is incorrect because the Organization of American States (OAS) was created in 1948, not in 1947. The OAS's own history page says the organization "came into being in 1948 with the signing in Bogotá, Colombia, of the Charter of the OAS."

What took place in Petrópolis/Quitandinha in August–September 1947 was a different event: the Inter-American Conference for the Maintenance of Continental Peace and Security. The U.S. Department of State's Office of the Historian identifies that 1947 meeting as that conference, not as a meeting of the OAS. The related treaty record in the United Nations Treaty Collection also shows the resulting Inter-American Treaty of Reciprocal Assistance was concluded in Rio de Janeiro on 2 September 1947.

So the article is wrong to say that the OAS met there on 15 August 1947; the organization had not yet been founded.

The infobox's mayor entry is outdated. Petrópolis's official municipal government website has a page identifying Hingo Hammes as "Prefeito". The municipality's own transition notice from 1 November 2024 also distinguishes Rubens Bomtempo from the incoming administration, stating that Rubens Bomtempo met with "o prefeito eleito, Hingo Hammes" to begin the transition.

That means Rubens Bomtempo was not the current mayor by the time the new administration took office; the city's own official pages identify Hingo Hammes as mayor instead.

The municipality area shown here does not match the current official figure from Brazil's national statistics agency, IBGE. On IBGE's city profile for Petrópolis, the municipality's Área Territorial is listed as 791.144 km² (reference year 2025), not 774 km².

Because the infobox presents the area without any historical date qualifier, readers are likely to understand it as the municipality's area; the official IBGE figure contradicts the value shown.

The problem here is the location of the signing. Official records from the Museu Imperial in Petrópolis state that the Treaty of Petrópolis was signed in the residence of the Baron of Rio Branco, on Rua Westphalia (now Avenida Barão do Rio Branco), not at Palácio Rio Negro.

The Museu Imperial's catalog entry for the Baron's residence explicitly says that in 1903 it was "where that year the Treaty of Petrópolis with Bolivia was signed." Another Museu Imperial record about the negotiators says they are photographed "na casa do barão do Rio Branco" and that the treaty was signed there on 17 November 1903.

So while the treaty itself is real, attributing its signing to Palácio Rio Negro is incorrect.