This comes from a poorly marked pile and I didn't scan it, I just took a photo.
The key is here-
I think that census map is for 1940 but attached documents say something about 1934, so I don't know which date these are for honestly. Anyway, the dark spots show "Residental Units Without Indoor Toilets" over 4%. The area of Shaw between NJ Ave and 7th Street had over 4% of households without toilets inside. Which means you either had to pee in a pot (usually sitting under a bed) or run outside to a outhouse, or both. You can see a photo of DC 1930 era outhouses/ poopshacks here.
The TC I must proudly point out had less than 2% of residental units without a indoor toilet. Same goes for U St and Logan Circle. Considering most of the houses in the TC were built around or after 1900 (based on census info not the property tax tax database) those homes most likely had indoor plumbing, particularly the ones built by the Washington Sanitary Improvement Company and Wardman. What does 4% look like? If you are in a bunch of rowhouses, count how many townhouses are on just your block or square. If you are in Old City, more than likely more than 50 homes. Now imagine 2 of those homes where the residents dump their human waste in the backyard.
Ain't history fun?