Smallest state park in the USA

From Gideon Lewis-Kraus’s “The Water Rush” (Oxford American):

Anywhere else, the four and a half acres of muddy, flat grass cross-hatched by asphalt paths and crowned by a green-pink-and-white gazebo would be the town park. Here in Berkeley Springs[, West Virginia], population 663, “the country’s first spa,” it is a state park. It is, in fact, the smallest state park in the nation. Along the embankment on the west side of the park is a camp of low-slung yellow-brick buildings that house the Berkeley Springs, font of the town’s hydrocentric entertainments. Besides the springs, the town’s attractions include antique malls, craft shops, acupuncturists, and a homeopathy museum.