First Security Bank, Sun River Valley Branch Basic Info Reviews Routing Numbers Map & Direction Name: First Security Bank, Sun River Valley Branch Main Office: No Service: Full Service Brick and Mortar Office Location: 390 Post Avenue Vaughn, Montana 59487 Cascade County View other branches Phone: 406-965-3074 Please enable JavaScript to view the comments powered by Disqus. Routing NumberProcess ACH TransferProcess Wire Transfer092900613YY092901175YY092904774YN From: To: