By chance I bumped into two profiles fitting data of Marius Schoonmaker, (April 24, 1811 – January 5, 1894) a United States Representative from New York:
Obviously these two profiles need merging and upgrading based on publicly available data. Same goes for profile of grandfather Cornelius C. Schoonmaker, also politician.
As a Dutchman I don't feel able to do that job, so...
Sadly, I estimate that there may be thousands (I do not think I am exaggerating) of former members of United States Congress who are not yet profiled in WikiTree, or maybe they have profiles but little or no indication of their having served in Congress. The Wikipedia profile for Cornelius C. Schoonmaker also is very, very rough.