You do SELECT from each table and perform UNION ALL operation on these results and finally insert the result into your third table.

Below is the final hive query:

INSERT INTO TABLE transaction_usa_canada
SELECT tran_id, acct_id, tran_date, amount, description, branch_code, tran_state, tran_city, speendby, tran_zip, 'transaction_usa' AS source_table FROM transaction_usa
UNION ALL
SELECT tran_id, acct_id, tran_date, amount, description, branch_code, tran_state, tran_city, speendby, tran_zip, 'transaction_canada' AS source_table FROM transaction_canada;

Hope this help you!!!