CREATE TABLE table_18656 ("District" CLOB, "Incumbent" CLOB, "Party" CLOB, "First elected" FLOAT, "Result" CLOB, "Candidates" CLOB)

What district has Riley Joseph Wilson as the incumbent?
SELECT "District" FROM table_18656 WHERE "Incumbent" = 'Riley Joseph Wilson'
SELECT "District" FROM "table_18656" WHERE "Incumbent" = 'Riley Joseph Wilson'