This dataset contains tree-ring data from plains cottonwood (Populus deltoides subsp. monilifera), narrowleaf cottonwood (Populus angustifolia) and their hybrids collected from floodplains within the Wind River Indian Reservation, Wyoming in 2017 and 2018. Samples were collected from trees at three sites: the Wind River upstream of Boysen Reservoir (latitude 43.127 N, longitude -108.232 W), the Wind River downstream of Diversion Dam (latitude 43.219 N, longitude -108.940 W) and Owl Creek near Arapaho Ranch, latitude 43.725 N, longitude -108.570 W. There are 3 files. Cottonwood_Wind_Tree_Data.csv contains descriptive information about each of the sampled trees, Cottonwood_Wind_Ring_Widths contains the tree-ring widths in Tucson format, and Cottonwod_Wind_READ_Me.txt duplicates some of the metadata in this metadata file in a format that is easy to read.