Who was in the 4th district in 1924?
CREATE TABLE "supervisors" (
  "year" real,
  "1st_district" text,
  "2nd_district" text,
  "3rd_district" text,
  "4th_district" text,
  "5th_district" text
);
SELECT "4th_district" FROM "supervisors" WHERE "year"=1924;