The Convenient Politically Fuzzy Economics of Government Agencies

Data at the Bureau of Labor Statistics (BLS) reveals that the legal definition of full-time appears to have been surreptitiously reduced to 35 hours for the benefit of making economic statistics conveniently, politically appealing. By lowering the bar of what is considered "full-time" to 35 hours, the BLS could easily report a higher percentage of alleged "full-time" employment.
Labor Force Statistics from the Current Population Survey page: http://www.bls.gov/cps/cpsaat08.htm

According to Wikipedia, "the Fair Labor Standards Act (FLSA) does not define full-time employment or part-time employment," However, according to People's World: "On October 24, 1940, the 40 hour work week went into effect under the FLSA. The new law had been signed by President Roosevelt in 1938."

http://www.peoplesworld.org/today-in-labor-history-the-40-hour-workweek/

My generation grew up with the assumption that full-time was 9am to 5pm Monday through Friday. At least until 1979 when the war on Unions and deregulation gained momentum. See these articles:

The Number of Salaried Workers Guaranteed Overtime Pay Has Plummeted Since 1979

http://www.epi.org/publication/the-number-of-salaried-workers-guaranteed-overtime-pay-has-plummeted-since-1979/

The expanding role of temporary help services from 1990 to 2008, Bureau of Labor Statistics, Tian Luo, Amar Mann, and Richard Holden; August 2010

-- http://www.bls.gov/opub/mlr/2010/08/art1full.pdf

There Are A Lot Of Part-Time Workers In Post-Financial Crisis America, Business Insider, Doug Shourt, Advisor Perspectives; November 10, 2014 -- http://www.businessinsider.com/ratio-of-part-time-employed-remains-substantially-higher-than-the-pre-recession-level-2014-11

Why The 40-Hour Workweek Is Dying, Forbes, Jayson DeMers; May 15, 2015 -- http://www.forbes.com/sites/jaysondemers/2015/05/15/why-the-40-hour-workweek-is-dying/

The Full-Time Job Is Dead, BackChannel, Kevin Maney; June 4, 2015 -- https://medium.com/backchannel/the-full-time-job-is-dead-b9528bda1c87