CREATE TABLE table_18637 ("District" CLOB, "Incumbent" CLOB, "Party" CLOB, "First elected" FLOAT, "Result" CLOB, "Candidates" CLOB)

what's the district with first elected being 1938
SELECT "District" FROM table_18637 WHERE "First elected" = '1938'
SELECT "District" FROM "table_18637" WHERE "First elected" = '1938'