After a strike in the '70s postal workers could bargain. This has led to stable, unglorified, mid pay jobs. The bargaining was and is key.
Now, if you sign up as a City carrier you can (with luck) become "regular" in 90 days. You will get 23 paid days off, eligible for federal pool health insurance (quite good 2m pool) where you pay 25% premium, never work Sundays, guaranteed 40 hours work a week, no email, stress, home by 5pm.
[1] https://wp1-ext.usps.gov/sap/bc/webdynpro/sap/hrrcf_a_unreg_...
Choose state and "delivery"