What state or province has the most staff living in it?
SELECT T1.state_province_county FROM Addresses AS T1 JOIN Staff AS T2 ON T1.address_id  =  T2.staff_address_id GROUP BY T1.state_province_county ORDER BY count ( * )  DESC LIMIT 1
most staff living in refers to MAX(COUNT(staff)); state or province refers to state_province_county;