CREATE TABLE "table1_225100_4" (
  "district" text,
  "vacator" text,
  "reason_for_change" text,
  "successor" text,
  "date_successor_seated" text
);

Question: What is the reason for change when maryland 6th is the district? 
SQL: SELECT "reason_for_change" FROM "table1_225100_4" WHERE "district"='Maryland 6th';

Question: Who is the vacator when south carolina 4th is the district?
SQL: SELECT "vacator" FROM "table1_225100_4" WHERE "district"='South Carolina 4th';

Question: Who is the successor when florida territory at-large is the district?
SQL: SELECT "successor" FROM "table1_225100_4" WHERE "district"='Florida Territory At-large';