CREATE TABLE table_18326 ("District" TEXT, "Incumbent" TEXT, "Party" TEXT, "First elected" FLOAT, "Result" TEXT, "Candidates" TEXT)

What district did S. William Green belong to?
SELECT "District" FROM table_18326 WHERE "Incumbent" = 'S. William Green'
SELECT "District" FROM "table_18326" WHERE "Incumbent" = 'S. William Green'