In which city are the most customers living in?
select t3.city from customers as t1 join customer_addresses as t2 on t1.customer_id = t2.customer_id join addresses as t3 on t2.address_id = t3.address_id group by t3.city order by count ( * ) desc limit 1
What about the city with least customers?
select t3.city from customers as t1 join customer_addresses as t2 on t1.customer_id = t2.customer_id join addresses as t3 on t2.address_id = t3.address_id group by t3.city order by count ( * ) limit 1
And in which state is it located?
select t3.state_province_county from customers as t1 join customer_addresses as t2 on t1.customer_id = t2.customer_id join addresses as t3 on t2.address_id = t3.address_id group by t3.city order by count ( * ) limit 1