Buckeye

This must be an Ohio Buckeye (Aesculus glabra).
The whole tree looked lush orange. Up close the leaf colors ranged from yellow to deep orange. Yummy colors.

Here's a photo of the deep orange part:



The shell/nut seed reminded me of a hazelnut inside a prickly walnut shell.



A similar tree, the horse-chestnut, is bigger and doesn't grow here.

ndsu1
"Ohio buckeye (Aesculus glabra) leaves have five to seven toothed leaflets arising at a common point (as the fans on a pinwheel). The leaflets are 3 to 6 inches long. The large showy flowers appear in clusters at the ends of the branches shortly after leafing in the spring. The fruit is a large, 1 to 2 inches in diameter, leathery capsule. It contains a large round chestnut-brown, shiny seed that contains a light colored spot at its base. Not native. New hybrid cultivars, medium-sized in stature, deserve greater attention for planting as residential and ornamental trees. Select 'Autumn Splendor' and 'Homestead' cultivars for leaf scorch resistance and reddish-orange fall color."

ndsu2
"The true horse-chestnut (A. hippocastanum) of the eastern and southern U.S. is beyond the range of hardiness in North Dakota.
If planted here it may suffer severe winter killing each year — if it survives at all.
The tree planted in North Dakota as buckeye (A. glabra) is hardy and also more variable.
Many hardy individuals are found growing well in North Dakota."

usda