Here are the schools that have the most MPA State Championships since 1970:

Boys
Yarmouth High School (Class B and C) 15
Falmouth High School (Class A, B and C) 12
Scarborough High School (Class A and B) 10
Richmond High School (Class C and D) 10
Greely High School (Class A and B)   8
Cape Elizabeth High School (Class A)   8
Georges Valley High School (Class C)   8
Bangor Christian School (Class D)   8
Waynflete School (Class C and D)   8
Gorham High School (Class A)   7
Brunswick High School (Class A)   7
North Yarmouth Academy (Class C and D)   7
St. Dominic Academy (Class C)   5
York High School (Class B)   4
Ellsworth High School (Class B)   4
Van Buren High School (Class D)   4
Bangor High School (Class A)   3
Lewiston High School (Class A)   3
Freeport High School (Class B)   3
Sacopee Valley High School (Class C)   3
Gray-New Gloucester High School (Class B)   3
Maranacook High School (Class B)   3
Washington Academy (Class C)   3
Marshwood (Class A)   3
Waterville High School (Class A)   2
Mt. Ararat High School (Class A)   2
Cheverus High School (Class A)   2
Lincoln Academy (Class B)   2
Machias (Class D)   2
Monmouth Academy (Class C)   2
Katahdin High School (Class C and D)   2
Morse High School (Class A)   1
Lawrence High School (Class A)   1
Windham High School (Class A)   1
Presque Isle High School (Class B)   1
Camden-Rockport High School (Class B)   1
Maine Central Institute (Class B)   1
Central Aroostook High School (Class D)   1
Shead High School (Class D)   1
Fort Fairfield High School (Class D)   1
Jonesport-Beals High School (Class D)   1
Fort Kent Community High School (Class C)   1
Traip Academy (Class C)   1
Wiscasset High School (Class C)   1
Carrabec High School (Class C)   1
Penobscot Valley High School (Class C)   1
Piscataquis Community High School (Class C)   1
Lee Academy (Class D) 1

Girls
Richmond High School (Class D) 11
Falmouth High School (Class B and C) 11
North Yarmouth Academy (Class C and D) 11
Cape Elizabeth High School (Class A and B)   9
Waynflete School (Class C and D)   8
Waterville High School (Class A and B)   7
Mt. Ararat High School (Class A) 7
York High School (Class B)   5
Windham High School (Class A and B)   5
Yarmouth High School (Class B)   4
Scarborough High School (Class A)   4
Gorham High School (Class A and B)   4
Camden Hills (Class A)   4
Schenck High School (Class C)   4
Greely High School (Class A)  
Van Buren High School (Class C and D)   3
Lee Academy (Class D)   3
Ashland High School (Class D)   3
Brunswick High School (Class A)   2
Deering High School (Class A)   2
Bangor High School (Class A)   2
Traip Academy (Class C)   2
Orono High School (Class C)   2
Southern Aroostook Community High School (Class D)   2
Georges Valley High School (Class C)   1
Caribou High School (Class B)   1
Central High School (Class C)   1
Fort Kent Community High School (Class C)   1
Westbrook High School (Class A)   1
Hyde School (Class B)   1
Penquis High School (Class B)   1
Mount Desert Island High School (Class B)   1
Mount View High School (Class B)   1
Houlton High School (Class C)   1
Fryeburg Academy (Class B)   1
Lisbon High School (Class B)   1
Winslow High School (Class B)   1
Carrabec High School (Class C)   1
Katahdin High School (Class C)   1
Searsport High School (Class C)   1
Dirigo High School (Class C)   1
Washburn High School (Class D)   1
Monmouth Academy (Class D)   1
Maranacook (Class C) 1
Bucksport (Class C) 1