In the previous posts, I identified properties on Sq. 552 (bounded by 1st, P, 3rd and Q Sts NW) owned by the Washington Sanitary Improvement Company (WSIC). This post looks at 1st Street.
This is real easy. There were none owned by WSIC.
The even side of the 1500 block of 1st St NW were lots 177-182 (1536-1526 1st St NW), 197-201 (1546-1538 1st St NW), and 163-175 (1524-1500 1st St NW). Looking at the 1933 General Assessment, these were owned by a variety of individuals, not the WSIC.