Divides

[froggie]

This is why I mentioned the tunnel on the Great Allegheny Passage. My brother's pictures show their group celebrating that they reached the top of the climb; from what I can find online, that seems to be a common theme for photos there. His pictures are from a different angle that make it look like a longer tunnel than it does here.

That would be the "tunnel" (which in reality is more like a path underpass) under the GMSV location I linked above.   It's close to the ECD, but the actual ECD location is about 500 feet behind the photographer in the photo you posted.

[Buck87]

As far as signage of water divides goes, Ohio has "Ohio River" and "Lake Erie" signs on I-75 to mark the divide.

I-71 has them as well, near Medina.

Not sure about I-77, but I doubt it has any signage since it crosses the divide 3 times in a 12 mile span with 2 of those being in the middle of Akron on either side of its east interchange with I-76. Speaking of I-76, it enters Ohio in the Ohio River watershed, briefly crosses part of the Lake Erie watershed from just south of Kent to just south of downtown Akron, then reenters the Ohio River watershed in which it remains for the rest of its route to I-71.

[US 89]

In contrast to the level of signage for lower-level continental divides in the eastern US, I have never seen the Great Basin Divide posted as such in any of the states it travels through. Often there will be a generic "summit elevation" sign at a crossing, but will make no reference to the hydrological divide.

From what I've observed, any mention of the hydrological divide would be on an interpretive sign at a rest stop, and even that is rare. Red Rock Pass in Idaho (US 91) has one because it was where Lake Bonneville overflowed. The other place I know I've seen the Great Basin Divide mentioned is in Bryce Canyon National Park, where the divide actually follows the top of the canyons/cliffs.