CREATE TABLE table_18316 ("District" CLOB, "Incumbent" CLOB, "Party" CLOB, "First elected" FLOAT, "Result" CLOB, "Candidates" CLOB)

How many parties are there in races involving Dawson Mathis?
SELECT COUNT("Party") FROM table_18316 WHERE "Incumbent" = 'Dawson Mathis'
SELECT COUNT("Party") FROM "table_18316" WHERE "Incumbent" = 'Dawson Mathis'