On Friday, Melissa Quinn at the Daily Signal, after the release of the government's "Union Members -- 2014" report, uniquely observed that the unionized percentage of the U.S. workforce had reached "its lowest rate in 100 years." From what I can tell in web and news searches, despite the fact that virtually any 100-year record is ordinarily considered newsworthy, no major establishment press outlet has reported what Quinn found.
The report from Uncle Sam's Bureau of Labor Statisics claims that 1983 is "the first year for which comparable union data are available." Perhaps, but there is data available going back much further, and it has been used occasionally in previous media reports. That data also indicates that private-sector union membership is at its lowest point since the turn of the century — from the 19th to the 20th century, that is.