Visit the above link for all the official rules and regulations for Field Day this year - June 23 & 24th, 2012. Local to the Springfield, MO area: SMARC (Southwest Missouri Amateur Radio Club) will be conducting Field Day activities at the Red Cross, corner of West Bypass and Division in Springfield; and the Nixa Amateur Radio Club will have Field Day at Nixa High Pointe Elementary (same location as last year).
More information can be found at http://smarc.org/?page_id=1937 for the SMARC event, and http://www.nixahams.net for the Nixa Amateur Radio Club event.
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OMAR