Approx. 4,150 occurrences on the net for this literal translation and true a lot of these are Brazilian sites, but there are also plenty of other international sites which have some type of Brazilian connection (business or academic):

http://www.google.com/#q="Rio-Sao Paulo axis"&hl=en&prmd=ivn...

e.g.
According to the points if view expressed in the FGV report, the principle ethics of the game will have to be revised as well as the qualifications of the professionals involved in the decision making process. The role of the media is extremely powerful in the Rio-Sao Paulo corridor, with the other regions coming in a distant second place in this context, and changes should, therefore, be aimed at restoring some form of equilibrium in the southeast of the country.
http://www.xtratime.org/forum/showthread.php?t=32370

The judiciary has suffered a scandal or two in the last year or so, including two cases from the Rio-São Paulo corridor involving senior judges accused of selling verdicts favoring organized crime interests such as illegal gambling enterprises.
http://cbrayton.wordpress.com/2008/02/

This more recent dichotomy again reflects various interesting and interconnected phenomena in Brazilian society: the urbanization and growth of towns in the interior of Brazil, outside of the dominant Rio—São Paulo corridor; the migration of middle-class citizens from these areas to the two metropolis, which has contributed to a mutual cultural influence; and, especially since the 1970’s, the emergence and recognition in the national scene of artists (especially musicians) from these various regions, in a movement that has expanded the repertoire of Brazil’s cultural voices.
http://jornalsidarta.blogspot.com/2011/03/tales-of-two-citie...