A handful of farmers in Ohio’s Mahoning County are getting an unpleasant lesson in government power at the hands of a local park district. Mill Creek MetroParks, a public agency governed by five unelected commissioners, wants to take over an abandoned railroad line running through about a dozen local farms for a recreational bike path. Last year, when landowners balked at the idea of strangers wandering across their properties, the park district decided to invoke eminent domain and gain right of way.

“I asked the park representatives if there was any way we could negotiate on this, and they told me, ‘The time for talking is over. We’re taking this property,’ ” says Ohio state Rep. Don Manning, who tried to intervene on the farmers’ behalf. Rep. Manning, a Republican, has sponsored legislation that would limit the use of eminent domain in Ohio.

The practice of government taking land for recreational uses—typically bike lanes, hiking paths and fashionable “rail trails” and “greenways”—is spreading across the country, marking a sharp and troubling expansion of eminent domain. The Takings Clause of the Constitution’s Fifth Amendment grants government the authority to seize property to be used for the public good, as long as government pays “just compensation” to the owner. Over the years, the Supreme Court has consistently expanded what is considered a “public good” to justify government seizures. In 2005, for instance, the high court upheld the taking of Susette Kelo’s waterfront home by the city of New London, Conn., so that a local development corporation could build high-end condos and a hotel. The redevelopment was intended to boost property values and increase municipal tax revenues.

Meanwhile, cities and towns across America have in recent years developed an appetite for different types of lengthy, sometimes intrusive hiking and bike paths. Advocates contend that such recreational amenities are vital because they promote alternative forms of transportation. Bike trails “are increasingly being used as a nonrecreational means of transportation, particularly by lower-income residents without access to a motor vehicle,” testified Jason Segedy, director of planning and urban development for Akron, Ohio, in opposition to Rep. Manning’s bill.

Municipal land grabs often result in bitter confrontations. Officials in Sioux City, Iowa, sought to complete a riverfront recreation trail in 2017 by offering Brad Lepper half of what an independent county commission had ruled his property was worth. Rather than pay up in full, the city invoked eminent domain, prompting Mr. Lepper to wage a two-year legal battle. He represented himself for much of the time.