CREATE TABLE table_2417390_4 (district VARCHAR2, date_successor_seated VARCHAR2)

What district was the successor seated in March 28, 1878?
SELECT district FROM table_2417390_4 WHERE date_successor_seated = "March 28, 1878"
SELECT "district" FROM "table_2417390_4" WHERE "March 28, 1878" = "date_successor_seated"