This is the Patriot Guard Riders:
They escort the living and departed veterans on their journeys. They escorted Pvt. Williams in relays all cross the country:
And 150 riders met him at the state line, to escort him back to Maine. Bravo Zulu.
If you're in Augusta, Maine, you can pay your respects to Pvt. Williams through mid September at the Maine Veteran's Memorial Cemetery, after which he will be buried next to his parents.
Hat tip (and thanks) to childhood buddy Rick for a pointer to this story.