It’s no secret that the U.S. Postal Service is looking at shutting more than 3,200 post offices as part of a major downsizing initiative. Less known is that 20 privately run post offices are also on the chopping block, but in this case because of a labor agreement with the American Postal Workers Union. Under its latest contract with the APWU signed last year, the Postal Service agreed to close 20 “contract postal units” (CPUs) or else insource the work “as soon as practicable.” Those units are in New York, Texas, Florida,Puerto Rico and several other states. Given that there are…