The cartels - specifically, the Zetas - are also tapping into oil pipelines, stealing the oil, shipping it northward into the US, and then selling it to various businesses. There was a Washington Post article last week on this activity, which is estimated to net over $700M a year...and it's particularly painful to the Mexican state which relies on oil revenues to fund the Federal Budget.

http://www.washingtonpost.com/wp-dyn...202888_pf.html

The shadow economy is growing like wildfire in Mexico. Also note the one Mexican minister stating that there is a "parallel government" within the state.