First Interstate Bank Online Banking First Interstate Bank was founded in 1928 in Los Angeles, California as First Interstate Bancorp. It became one of the largest banks of the United States. In 1996, it was taken over by Wells Fargo then became a subsidiary of the First Interstate Bank System. Customer Service Telephone 1(888) 752-3332 Online Banking Login How to Log In 1. Go to the First Interstate Bank website. 2. Select the service you would like to log into.…