The loss of farmland near United States urban areas is a slow-motion tragedy that has been taking place for decades.

Rep. Mike Thompson, D- St. Helena, is taking productive steps to slow it. Thompson has successfully pushed, and is pushing again, for legislation providing strong financial incentives for property owners to keep their land free of urban development.

A week ago today, Thompson and a co-sponsor introduced H.R. 1831, which would make permanent a tax break for farm and ranch owners who set aside their land under conservation easements. Such easements are essentially binding promises to keep land in open space for as long as the owner has it, and for the owners to make the protections a condition of sale should the land change hands.

An existing law, sponsored by Thompson four years ago, gives owners tax breaks on the value of the land they place into such easements. That law expires at the end of this year. The new measure would make the tax breaks permanent.

This existing measure has helped many of the country’s 1,700 or so land trusts — including the Land Trust of Napa County and the Sonoma Land Trust — to work with sympathetic landowners who want to keep their land free of development.

David Duff is one example. Last year the owner of the 1,000-acre Duff Ranch near Calistoga sold his property to the Land Trust of Napa County.

“I am intimate with the land, so I know it more than anybody,” Duff told the Register in December. “There is no way I was going to sell to a developer.”

Critically, the easements also ease the tax burdens that might otherwise force people to sell farms that have long been in the family.

The co-sponsor of Thompson’s bill, the Conservation Easement Incentive Act, is Republican Eric Cantor of Virginia. Cantor’s large district includes vineyard properties, rolling farmlands and historic Civil War sites near towns that are under pressure to grow into suburbs of Washington, D.C.

The problems Thompson is seeking to address cross party and state lines. We applaud this effort to keep our land and our heritage alive and thriving.