In what district was the successor seated August 31, 1943?
CREATE TABLE "table1_2159537_3" (
  "district" text,
  "vacator" text,
  "reason_for_change" text,
  "successor" text,
  "date_successor_seated" text
);
SELECT "district" FROM "table1_2159537_3" WHERE "date_successor_seated"='August 31, 1943';