SELECT rid FROM routes WHERE dst_apid IN (SELECT apid FROM airports WHERE country  =  'United States') AND src_apid IN (SELECT apid FROM airports WHERE country  =  'United States')
Find the id of routes whose source and destination airports are in the United States.
SELECT rid FROM routes WHERE dst_apid IN ( SELECT apid FROM airports WHERE country = 'United States ' ) AND src_apid IN ( SELECT apid FROM airports WHERE country = 'United States ' )
select rid from routes where dst_apid in ( select apid from airports where country = value ) and src_apid in ( select apid from airports where country = value )
Find the id of routes whose source and destination airports are in the United States .