-Letter carriers are part of the National Association of Letter carriers.
-Clerks, truck drivers, mechanics and maintenance are part of the American Postal Workers Union
-Mail-handlers are part of the National Postal Mail-handlers Union
-Rural carriers are part of the National Rural Letter Carrier Association
All four have separate contracts so it must really suck to be management. APWU and NALC are the by far the strongest. I’m not sure why there are four separate ones but I’m assuming only one would have too much power.