In 2018, 7.2 million employees in the public sector belonged to a union, compared with 7.6 million workers in the private sector. Union membership rates for both public-sector and private-sector workers edged down in 2018. The unionization rate in the [119M total] private sector (6.4 percent) remained substantially below that for [21M total] public-sector workers (33.9 percent). Within the public sector, the union membership rate was highest in local government (40.3 percent), which employs many workers in heavily unionized occupations, such as police officers, firefighters, and teachers. Private-sector industries with high unionization rates included utilities (20.1 percent), transportation and warehousing (16.7 percent), and telecommunications (15.4 percent). Low unionization rates occurred in finance (1.3 percent), food services and drinking places (1.3 percent), and professional and technical services (1.5 percent). (See table 3.)

BLS union figures supposedly include P/T and "covered" contract employees in both sectors; guessing here that ag sector is not joined with "private" sector. Note discrepancy between imputed 2018 total non-farm and published estimates for 2018. The Employment Situation for February 2019 is scheduled to be released on March 8, 2019.

Diversity is the key to economic and political evolution.