Athmar Park is bordered by Alameda avenue on the north, Mississippi avenue on the south, Federal boulevard on the west and the South Platte River on the east. Four Denver parks, Aspgren, Huston Lake, Vanderbilt Park and Habitat Park, exist within the boundaries of Athmar Park. The eastern half of the neighborhood is lower in elevation than the west, with a sharp rise above the river beginning near Pecos Street and continuing the gradual climb in elevation toward the southwest.

Historically, Athmar Park was annexed incrementally by the City of Denver. In 1902 the eastern edge of Athmar Park was annexed, along with the town of Valverde, from Zuni to the South Platte River border. In 1932 the area west of Zuni was annexed by the City of Denver. The area west of the town of Valverde that had originally been in the hands of three different owners was auctioned and purchased by Thomas and John R. McCusker in 1946 and developed into the subdivision of Denver named "Athmar Park"