CREATE TABLE table_204_507 (id DECIMAL, "bridge name" TEXT, "location" TEXT, "year completed" DECIMAL, "total length" TEXT, "carries" TEXT)

how many bridges are 400 feet long at most ?
SELECT COUNT("bridge name") FROM table_204_507 WHERE "total length" <= 400
SELECT COUNT("bridge name") FROM "table_204_507" WHERE "total length" <= 400