CREATE TABLE table_203_591 (id DECIMAL, "high school" TEXT, "join\ year" TEXT, "from" TEXT, "left" TEXT, "league left to" TEXT)

list each of the high schools which joined in the year 1976 .
SELECT "high school" FROM table_203_591 WHERE "join\nyear" = 1976
SELECT "high school" FROM "table_203_591" WHERE "join\nyear" = 1976