From the St. Louis Post-Dispatch:
The federal government has spent millions of dollars to help farmers nationwide buy greenhouse-like structures called high tunnels that can add valuable weeks and even months to their growing seasons by protecting produce from chilly temperatures.
About $13 million has gone to more than 2,400 farmers in 43 states to help pay for the low-tech tunnels that look like a cross between Quonset huts and conventional greenhouses. The structures, also known as hoop houses, have been particularly beneficial in the north, where they allow farmers to plant as much as four weeks early and keep growing later in the fall.
The U.S. Department of Agriculture touts the tunnels as environmentally friendly and a way to help meet the demand for local and sustainable produce. Experts say high tunnels employ efficient drip irrigation systems and reduce pest problems, diseases and fertilizer costs.