CREATE TABLE table_name_20 (district VARCHAR2, first_elected VARCHAR2, incumbent VARCHAR2)

Which District has a First elected of 1856, and an Incumbent of william kellogg?
SELECT district FROM table_name_20 WHERE first_elected = 1856 AND incumbent = "william kellogg"
SELECT "district" FROM "table_name_20" WHERE "first_elected" = 1856 AND "incumbent" = "william kellogg"