|São Paulo state flag|
The São Paulo state flag is actually a national flag reject (hence the pictorial representation of the country not the state). It was supposed to serve as the Republican flag in 1889 but a rival design, which is similar to the current Brazilian flag, was eventually chosen. The paulista flag then laid dormant until it was adopted by the state of São Paulo in 1946 by which time the prohibition of state symbols and flags had been lifted.
Although when proposed as a national flag the colours black, white and red were supposed to reflect the racial diversity of the country; European (white), African (black) and Indigeneous (red), as state flag the elements have the following meaning:
The 13 black and white stripes: The nights (black) and days (white) during which the bandeirantes fought for the state.
[ASIDE: The word bandeirantes derives from the portuguese word bandeira or flag. They are the guys who, organising themselves through a system of identifying flags, basically fought, robbed and enslaved indigeneous peoples despite being themselves descendents or partially descendent of indigenous tribes. So, although they were essentially land pirates and have a deservedly bad name elsewhere in South America, in Brazil and in São Paulo in particular they are revered for setting out from São Paulo de Piratininga (now São Paulo) and contributing to making Brazil stretch out way beyond the dividing lines the Portuguese and the Spanish had formally agreed. True heroes..]
The red triangle represents the blood spilt by the bandeirantes in their exploits
The colour blue is supposed to reflect the strength and vigour which was given to the state (and presumably country) by the bandeirantes.
And finally the 4 stars are supposed to be the four major stars of the constellation of the Southern Cross (Cruzeiro do Sul) under which Brazil, and therefore São Paulo, lies.