I can already find data about Brazilian cities/states (e.g. population, localization, crime rates etc...), on some websites such as the government's open data portal and census data (which unfortunately is a mess).
Is there any API for this information, that would make it easier to query?
Both the Brazilian Community CKAN instance http://br.ckan.net/dataset and the Brazilian Government's official Data Portal (CKAN-powered) which you link to, have APIs.
There's also the World Bank API: http://data.worldbank.org/
You could use dbpedia and its sparql endpoint for this. The following SPARQL query would return all metrics except crime rates, you asked for.
PREFIX dbo: <http://dbpedia.org/ontology/>
PREFIX dbr: <http://dbpedia.org/resource/>
PREFIX dbp: <http://dbpedia.org/property/>
SELECT * WHERE {
?city rdf:type dbo:City .
?city foaf:isPrimaryTopicOf ?wikipediaPage .
?city dbo:country dbr:Brazil .
?city rdfs:label ?cityLabel .
?city dbp:populationTotal ?population .
?city <http://www.w3.org/2003/01/geo/wgs84_pos#long> ?longitude .
?city <http://www.w3.org/2003/01/geo/wgs84_pos#long> ?latitude .
}
All the attributes that are mentioned in for example the dbpedia entry of Sao Paolo are available through sparql queries.
