Six hikers have reached a plateau near Mansfield Mountain’s top and are ready to picnic just before sunset. Thompson titled the painting a Belated Party to provide tension, and we wonder if the picnickers will safely walk down the 4400-foot mountain in the evening darkness. It’s a likely assumption to think they would not go down in the dark. But it’s probably a safe assumption they might lodge at the Summit Hotel, a hotel for sightseers on the mountain. 
Selectively choosing his details, Thompson does not acknowledge the road or the hotel. These details would make the situation less rugged and sublime. It’s an application of the often-used technique of artistic license. Thompson was an admirer of Thomas Cole and might have known that he recreated Mount Holyoke’s summit to suit his View from Mount Holyoke, Northampton, Massachusetts, after a Thunderstorm– The Oxbow (1836).
See Jerome Thompson. The Belated Party on Mansfield Mountain (1858). Metropolitan Museum of Art; Lee M. Edwards, “The Life and Career of Jerome Thompson,” American Art Journal 14(4) Autumn 1982, 4 -30; Donna Brown. “Accidental Tourists: Visitors to the Mount Mansfield Summit House in the Late Nineteenth Century.” https://vermonthistory.org/journal/misc/AccidentalTourists.pdf