CREATE TABLE table_8471 ("South or west terminus" TEXT, "North or east terminus" TEXT, "First year" FLOAT, "Final year" FLOAT, "Notes" TEXT)

What is the most minimal Final year that has a North or east end of covington?
SELECT MIN("Final year") FROM table_8471 WHERE "North or east terminus" = 'covington'
SELECT MIN("Final year") FROM "table_8471" WHERE "North or east terminus" = 'covington'