Here is a list of Dallas area public and private schools listed by number of National Merit Semifinalists for 2013.
The 2014 list released Sept 2013 is here:
http://dallas-area-schools.blogspot.com/2013/09/2014-national-merit-semifinalists.html
# of Semifinalists - school (district)
48 - Plano West (Plano ISD)
46 - Flower Mound (Lewisville ISD)
44 - Plano (Plano ISD)
41 - Texas Academy of Math/Science (public residential)
35 - Plano East (Plano ISD)
24 - Hockaday (private, girls only)
21 - Coppell (Coppell ISD)
18 - Marcus (Lewisville ISD)
18 - Paschal (Fort Worth ISD)
18 - St. Mark's School of Texas (private, boys)
14 - Southlake Carroll (Carroll ISD)
12 - Hebron (Lewisville ISD)
12 - Highland Park (Highland Park ISD)
12 - Homeschoolers
10 - Greenhill (private)
10 - Talented & Gifted magnet (Dallas ISD)
9 - Cistercian (private, boys)
9 - Jesuit (private, boys)
8 - Fort Worth Country Day (private)
8 - JJ Pearce (Richardson ISD)
7 - Liberty (Frisco ISD)
7 - Oakridge School (private)
7 - Trinity Christian Academy (private)
7 - Ursuline (private, girls)
6 - Creekview (Carrollton-Farmers Branch ISD)
5 - Allen (Allen ISD)
5 - Boyd (McKinney ISD)
5 - Colleyville Heritage (Grapveine-Colleyville ISD)
5 - Grapevine (Grapevine-Colleyville ISD)
5 - Keller (Keller ISD)
5 - Martin (Arlington ISD)
4 - Episcopal School of Dallas (private)
4 - Lake Highlands (Richardson ISD)
4 - LD Bell (HEB ISD)
4 - Lovejoy (Lovejoy ISD)
4 - McKinney (McKinney ISD)
4 - Ranchview (Carrollton-Farmers Branch ISD)
4 - Trinity Valley (private)
3 - Berkner (Richardson ISD)
3 - Cambridge School (private)
3 - Garland (Garland ISD)
3 - Lewisville (Lewisville ISD)
3 - Richardson (Richardson ISD)
3 - Northwest (Northwest ISD)
3 - Science & Engineering magnet (Dallas ISD)
3 - The Colony (Lewisville ISD)
3 - Timberview (Mansfield ISD)
2 - Arlington High (Arlington ISD)
2 - Bishop Lynch (private)
2 - Boswell (Eagle Mountain - Saginaw ISD)
2 - Central (Keller ISD)
2 - Frisco (Frisco ISD)
2 - Lakehill Prep (private)
2 - Parish Episcopal (private)
2 - Pope John Paul II (private)
2 - Prestonwood Christian Academy (private)
2 - Rockwall (Rockwall ISD)
2 - Ryan (Denton ISD)
2 - Wakeland (Frisco ISD)
2 - Wylie (Wylie ISD)
1 - Aledo (Aledo ISD)
1 - Argyle (Argyle ISD)
1 - Bethesda Christian (private)
1 - Birdville (Birdville ISD)
1 - Burleson (Burleson ISD)
1 - Canterbury Episcopal (private)
1 - Centennial (Frisco ISD)
1 - Duncanville (Duncanville ISD)
1 - Faustina Academy (private)
1 - Halton (Birdville ISD)
1 - Harmony Science (charter)
1 - Highlands School (private)
1 - Hillcrest (Dallas ISD)
1 - Lamar (Arlington ISD)
1 - Legacy (Mansfield ISD)
1 - Lewisville iSchool
1 - Liberty Christian (private)
1 - Mansfield (Mansfield ISD)
1 - MacArthur (Irving ISD)
1 - McKinney Christian (private)
1 - Nimitz (Irving ISD)
1 - Nolan Catholic (private)
1 - North Hills Prep (charter)
1 - North (McKinney ISD)
1 - Pantego Christian (private)
1 - Prince of Peace Christian (private)
1 - Prosper (Prosper ISD)
1 - Richland (Birdville ISD)
1 - Royse City (Royse City ISD)
1 - RL Turner (Carrollton-Farmers Branch ISD)
1 - Saginaw (Eagle Mountain - Saginaw ISD)
1 - Southwest Christian (private)
1 - Summit (Mansfield ISD)
1 - Trinity (HEB ISD)
1 - Western Hills (Fort Worth ISD)
1 - Westlake Academy (charter)