CREATE TABLE table_18631 ("District" TEXT, "Incumbent" TEXT, "Party" TEXT, "First elected" FLOAT, "Result" TEXT, "Candidates" TEXT)

William Fadjo Cravens serves the fourth district of Arkansas.
SELECT "District" FROM table_18631 WHERE "Incumbent" = 'William Fadjo Cravens'
SELECT "District" FROM "table_18631" WHERE "Incumbent" = 'William Fadjo Cravens'