[kcvv]

It would be an interesting problem to see / solve where in this map would a drop travel the most. By just clicking, I got one that travels from Cavour, South Dakota to Gulf of Mexico over a 3523 Kms journey. I am sure there must be something that is longer!

Edit - some of the routes stop at border of Canada - is this due to lack of dataset?

[carl_dr]

The source of the Missouri River - Brower's Spring apparently - is probably close to the point where it's longest. I can't find it exactly on this map, but have got up to 5790km, from a point just by Yellowstone Airport.

The code is at https://github.com/sdl60660/river-runner/, it would be quite possible to base a solver on that.

[samlearner]

Ha I appreciate you sharing the repo, but if someone is interested in finding a longest route, they should probably just go straight to the data source (USGS NHDPlus data/NLDI API)

[Sharlin]

The longest route in this dataset is almost certainly from Northwest Montana to the Gulf of Mexico; see, eg. the beautiful illustration of watersheds in North America at [1]. Example: [2]

[1] https://www.visualcapitalist.com/maps-worlds-watersheds/

[2] https://river-runner.samlearner.com/?lng=-113.26136901231438...

[TimonKnigge]

You can click in Northern Montana for longer routes, e.g. Browning, Montana gives about 5587km.

[kcvv]

This is cool! Did you have some info on this or use some data to find this? I was randomly clicking points on center of US and many were just ending in a nearby lake. I only found a few that ended up in the sea..