It's fun to find a photo which is well understood by an archive, and provide information which was missing or inaccurate.
The Library of Virginia's maximum size is pretty lowres, and I couldn't find the photo on their website. But man, it seemed like I could almost make out the name of the ship above the bridge...
After searching with a number of guesses, I finally found the name of the ship carrying home these medics from The Great War. It's the Walter A. Luckenbach. (more photos onboard)
When I read through its history, I discovered that this ship was built in Seattle, at the Seattle Construction and Dry Dock Company. NOAA's got a great photo of the dry dock in 1912. That pier is now Pier 36 on Seattle's waterfront, local home of the Coast Guard. The UW Library has another shot looking out over the water a dozen years later.
It looks like they've tagged the photo with the wrong year. According to the Dictionary of American Naval Fighting Ships History, the Walter A. Luckenbach transported troops from France in five runs from January 22 to July 11 1919.
I'm guessing that a more exact date can be pulled from the book "U.S. Army Base Hospital No. 45 in the Great War", at least down to the time they were on board. I don't have a copy, but I know a certain library in Virginia that does.
(This is a combination of comments in the photo and a post in the Flickr Commons group research thread.)