CREATE TABLE table_203_400 (id DECIMAL, "district" TEXT, "vacator" TEXT, "reason for change" TEXT, "successor" TEXT, "date successor\ seated" TEXT)

which district is listed last on this chart ?
SELECT "district" FROM table_203_400 ORDER BY id DESC LIMIT 1
SELECT "district" FROM "table_203_400" ORDER BY "id" DESC NULLS LAST LIMIT 1