CREATE TABLE table_18164 ("District" TEXT, "Incumbent" TEXT, "Party" TEXT, "First elected" FLOAT, "Results" TEXT, "Candidates" TEXT)

When was the incumbent in the Tennessee 4 district first elected?
SELECT "First elected" FROM table_18164 WHERE "District" = 'Tennessee 4'
SELECT "First elected" FROM "table_18164" WHERE "District" = 'Tennessee 4'