Here's a pretty interesting tool to tell you about the location of postal services in your neighborhood.
By visiting the USPS interactive map and entering a ZIP Code, you can find all kinds of postal information.
"Where's a collection box?"
"Where can I buy stamps?"
"Where can I send a package?"
"Where's nearest APC?"
and much more...
The only thing it doesn't tell you is where you left your keys.
That's another federal agency's job.