You can now use Amazon Route 53 private Domain Name System (DNS) and health checks for public endpoints in the AWS GovCloud (US-West) Region. This AWS Region is designed to host sensitive data and regulated workloads in the cloud for customers who have U.S. federal, state, and local government compliance requirements.

from Recent Announcements https://aws.amazon.com/about-aws/whats-new/2019/05/amazon-route-53-launches-private-dns-and-health-checks-in-the-aws-govcloud-us-west-region/