Ok, I was curious when it showed up on my grandfather's baptism record back in Oct (in the matrimony register=marriage date for my grandparents), and figured it had to mean something but just wasn't sure. Didn't want to knock it as just a mistake or misprint, it was there for a reason. Wasn't sure I could google it.

Then I received my grandmother's employment records, she worked for the government, this past week and I seen it again. Washington 25, D.C.

What Does this mean and why is it written this way?

I am googling it and see that it is common, but no explanation. Anyone has an explanation?

Thanks