Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE routes ( rid VARCHAR, dst_apid VARCHAR, src_apid VARCHAR, apid VARCHAR, country VARCHAR )
TABLE: CREATE TABLE airports ( rid VARCHAR, dst_apid VARCHAR, src_apid VARCHAR, apid VARCHAR, country VARCHAR )

### Question ###
Find the id of routes whose source and destination airports are in the United States.

### Accurate SQL ###

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')