Pioneer High School is part of the Whittier Union High School District in Whittier, California. <p>The Pioneer High School website uses frames. We recommend you update your browser. <p> Pioneer High School opened on September 14, 1959. Four Pioneer High School classes have announced reunion plans for 2007. Check our reunion page for details. <p> It's Confirmed: Click Here for Official Announcement <br> The class of 1976 is planning a 30ish reunion party to be held Friday May 25, at Maggies Pub - 11900 Telegraph Rd. Santa Fe Springs, CA. The cost is $35 and includes Cocktail appetizer menu, Music, Prizes. For more information contact Joey Duran at or Irene Mora at . Or, you can also call Irene at (562) 696-7607.