These data are high-resolution bathymetry (riverbed elevation) in compressed LAS (*.laz) format, generated from the July 17–18, 2023, hydrographic survey of the North Branch Chicago River and North Shore Channel in Cook County, Illinois. The survey extends from near the North Avenue Turning Basin and Goose Island in the south, upstream to the Metropolitan Water Reclamation District (MWRD) Wilmette Pumping station in the north. The survey is a continuation of the bathymetric survey of the Chicago River and Chicago Sanitary and Ship Canal (CS&SC) in Cook County, Illinois, conducted August 22–24, 2022 (Huizinga and Rivers, 2023). These data also include an ultra-high resolution resurvey of a large sunken vessel discovered in August 2022 in the eastern channel near Goose Island. Hydrographic data were collected using a high-resolution multibeam echosounder mapping system (MBMS), which consists of a multibeam echosounder (MBES) and an inertial navigation system (INS) mounted on a marine survey vessel. Data were collected as the vessel traversed the river along overlapping longitudinal survey lines distributed throughout the reach. Data collection software integrated and stored the depth data from the MBES and the horizontal and vertical position and attitude data of the vessel from the INS in real time. Data processing required specialized computer software to extract bathymetry data from the raw data files and to summarize and map the information. The full-resolution data are provided in American Society for Photogrammetry and Remote Sensing (ASPRS) compressed LAS format as NChicagoRivChannel_bathymetry_2023-07_fullres.laz. This bathymetry dataset is the full-resolution, near-raw data output from the processing software. This dataset has undergone limited cleanup and editing to remove obvious stray data and aquatic vegetation, but data editing was minimized to retain detail. Furthermore, this dataset is large, and may not be readily viewable without specialized software. The reduced-resolution data also are provided in ASPRS compressed LAS format as NChicagoRivChannel_bathymetry_2023-07.laz. This bathymetry dataset is a subset of the full-resolution data in the NChicagoRivChannel_bathymetry_2023-07_fullres.laz file, reduced to a nominal 0.5-meter point spacing. The compressed LAS format is a standardized binary format for storing 3-dimensional point cloud data and point attributes along with header information and variable length records specific to the data. Data points are stored as a 3-dimensional data cloud as a series of x (longitude), y (latitude), and z (elevation) points. Please refer to http://www.asprs.org/Committee-General/LASer-LAS-File-Format-Exchange-Activities.html for additional information. Reference Cited: Huizinga, R.J., and Rivers, B.C., 2023, Chicago River and Chicago Sanitary and Ship Canal bathymetry in Cook County, Illinois, August 2022: U.S. Geological Survey data release, https://doi.org/10.5066/P94TL2PV.