origin changes to 53170
what to do to fix it.
So, I recreated your issue and found that it does change to 53170 but I also see that it refers to an location in france.
But when I specify in both origin and destination the country:
origins=53022, USA
destinations=35210, USA
this is what i get:
"destination_addresses":[ "Birmingham, AL 35210, USA" ],
"origin_addresses":[ "Germantown, WI 53022, USA"]
even thou the numbers stays correct I see that is not in DC.
My advice is the more specific your addresses are, the better results from google you will have, your query is no very specific so google try to make sense of it to its own way and give you thouse results.
Happy Coding :)