<p>Article in Washington Post last Feb said not all the DC winners live in DC, some live in MD and VA and attend school in DC, so I would infer that it is where you attend school.</p>
<p>“Last year, nine students in D.C. schools were named National Merit finalists. Only four were D.C. residents, and only one of the nine attended a public school, Wilson High School. The rest attended private schools.”</p>
<p>[The</a> Answer Sheet - D.C.'s National Merit winners aren’t all from D.C.](<a href=“http://voices.washingtonpost.com/answer-sheet/dc-schools/poor-washington-dc-not-only.html]The”>http://voices.washingtonpost.com/answer-sheet/dc-schools/poor-washington-dc-not-only.html)</p>