US Highways at Moran Jct. WY and the
South Entrance to Yellowstone National Park

Note: since I don't have access to a comprehensive collection of historical road atlases, much of the info on this page is based on the research of Robert Droz; click here to view his site. Photo credits: Chris Elbert

Among roadfans, it's a well-publicized fact that US routes are not signed through Yellowstone National Park, and the south entrance to the Park is commonly cited as the southern point of interruption for the routes listed above. That may have been true in the past, but today the highway is actually not signed anywhere north of Moran Junction (that's in Grand Teton National Park, about 30 miles south of the Yellowstone park boundary). Below is a photo from there:

Elbert, July 2005

In the background, part of the Teton Range is visible. That's coming from Dubois (pronounced DOO-boyz) on northbound US 287/westbound US 26 (straight ahead leads south to Jackson via southbound US 89 and US 191, but technically that should be "West" on US 26, not "South"). Straight ahead was also the north beginning of US 187 from the 1950's until 1982. Chris reports that if you take a right here, there are no reassurance markers until the far side of Yellowstone. (At the Colter Bay Visitor Center - which is about a mile off the main highway - he did observe a sign with the text "To US 89", but US 191/287 were not mentioned.) He also reports that he did not see any directional signage for a driver heading south here (such as the white pickup in the background), which I would consider a remarkable oversight. The photo below is looking the opposite direction - north on what is now eastbound US 26/northbound US 89/US 191:

Elbert, July 2005

US 26 continues ahead (with southbound US 287) over Togwotee Pass (pronounced TOG-uh-tee, I believe) towards Dubois. Northbound US 89/191/287 goes left to Yellowstone's south entrance (although, as I've said, this is the last sign you'll see). Pre-1982, things were the same at this junction, except US 187 ended here, and US 191 didn't run through these parts. In 1982, US 187 was decommissioned, because US 191 was extended southward via an implied route through Yellowstone National Park, swallowing up the entirety of what had been US 187. To the left, the road travels through 21 more miles of Grand Teton NP. Then there is an 8-mile stretch through a sort of buffer protection zone known as the John D. Rockerfeller, Jr. Memorial Parkway. After that, you reach the Yellowstone park boundary...

Elbert, July 2005

...and the historic interruption point for US 89, 191, and 287 (and before 1965, this was actually the north endpoint of US 287). Today both US 287 and US 191 resume at West Yellowstone, while US 89 reappears at the Park's north entrance.