Mt. Denali:

The Highpointers Club is made up of the 280 people who have ascended the highest point in all 50 states.  The highest points in some states are quite challenging from a mountaineering perspective.  Mt. Denali in Alaska is 20,310 ft.; Mt. Whitney in California is 14,505 ft; Colorado’s Mt. Elbert is 14,440; Nevada, New Mexico, Utah and Montana all have highest points over 12,000 ft; and Mt. Ranier in Washington clocks in at 14,417.

The states with relatively low-lying points have their own challenges.  While some are in state parks, such as Missouri’s Mt. Taum Sauk (1,772ft) and New Jersey’s High Point (1,803ft), others are on private property such as Nebraska’s Panorama Point (5,429ft) found on a private ranch and Charles Mound (1,235ft) in Illinois on a farm. Delaware’s highest point (448 ft) is along a roadside near Wilmington. Florida’s highest point is in a remote location in the Florida panhandle (Lakewood Park 345ft).

Illinois’ highest point “Charles Mound”:

Source: https://www.wsj.com/articles/to-ascend-the-peak-of-every-state-climbers-must-reckon-with-florida-1489073490

Thanks to Michael Small to passing on this very interesting information.