Mexico in the 70's was building a middle class until it slashed spending on transportation, health care, and education. Poof. As an article from 2002 in the New York Times said:
The development of a middle class was a shining achievement of the Mexican revolution, said the historian Lorenzo Meyer. Incubated in a closed economy that was driven by state-owned monopolies, the middle class grew steadily from the 1920's to the 1970's. Faced with declining economic efficiency and a mounting public debt, successive presidents opened Mexico's protected economy, igniting an industrial revolution that turned the country into one of the world's leading exporters.
In an effort to reduce its external debt, the government simultaneously slashed spending for higher education, transportation and health care - all traditional pillars of middle-class life. Found here.