For US Banks - the information can be obtained in the following website:
Instructions for Obtaining List of US Banks and ABA Routing Number
1). Go to website www.FedEDirectory.FRB.ORG
2) Click on Download E-Payments Routing Directories
3) Scroll down to the bottom of the page and double click on
4) The file will appear in *.txt format which you can then save to your desktop.
5) The file layout/format (fixed length) can be determined in the link which appears at the bottom on the screen.
6) You can then open the file and parse the data using the information in the file format.
7) You may encounter issues with the certificate. Click on the Frequently Asked Questions link at the top under the title Federal Reserve E-Payments Routing Directory – there are many good tips in this link if you encounter a problem.