From the USPTO:
On August 12, 2016, the informational web pages currently found at http://www.uspto.gov will be moved to https://www.uspto.gov. The pages will now use HTTPS (Hypertext Transfer Protocol Secure), the strongest privacy and integrity protection currently available for public web connections.
Those accessing web pages formerly found at http://www.uspto.gov will automatically be redirected to the pages’ new https location. Many of our systems already use the https protocol, and we continue to work to update all our systems to HTTPS as part of a government-wide effort to ensure all federal websites use HTTPS. Using HTTPS ensures a new, strong baseline of user privacy and security across U.S. government websites and APIs.
No outage is anticipated during this change, and we expect user impact to be minimal. For the latest information about the upgrade to https and other changes to our online systems , visit the USPTO system status webpage.