During the 1920s, the British-controlled rubber plantations of Southeast Asia had driven prices up to what Detroit considered intolerable levels. Every automobile needs tires, and every tire then required natural latex from Hevea brasiliensis, a tree native to the Amazon basin but, by a historical accident, successfully cultivated only in British Malaya and Ceylon. The US Department of Commerce encouraged American companies to find alternative supplies. Ford took the challenge seriously. The logic was simple: Hevea brasiliensis came from Brazil. Grow it in Brazil, ship it to Dearborn, free Ford Motor Company from British price-setting. The execution was harder. The leaf-blight fungus Microcyclus ulei, which had co-evolved with the tree and kept wild populations sparse enough to resist infection, thrived on plantation monocultures.

Belterra's site sat 165 meters above sea level at the edge of the Planalto escarpment, some 40 kilometers south of Santarem. The flat topography, which had disqualified Fordlandia, was the reason Belterra got built; machinery could work the ground where Fordlandia had demanded entirely manual labor. Soil scientists now know the plateau is also famous for something older: it carries some of the best-documented deposits of terra preta, the anthropogenic dark earth that indigenous Amazonian societies created through centuries of composting, burning, and farming. Radiocarbon analyses of ceramic fragments pulled from Belterra's terra preta show that people have been cultivating this ground intensively since at least 500 BC. Ford's agronomists may not have fully understood what they had, but the indigenous farmers who built that soil over millennia gave his plantation one of its few real advantages.

At its peak in the late 1930s, roughly 50 square kilometers of Belterra were cultivated with Hevea brasiliensis. At its fullest the town held 8,000 to 10,000 people, most of them Brazilian workers and their families living in a landscape engineered to resemble Michigan. Ford built identical wooden bungalows with screened porches, installed a water tower that would have looked at home in any Midwestern suburb, planted lawns, opened a school and built a hospital. Ford's rules came with the housing: no alcohol, no tobacco, and weekend square dances that few of the workers had asked for. The agronomists here applied new breeding methods using local varieties in an effort to defeat the leaf blight that had wrecked Fordlandia's monoculture. The effort succeeded biologically, up to a point, but it was enormously labor-intensive and therefore expensive.

By 1945 the whole experiment had become untenable. Synthetic rubber, developed during World War II, made natural latex far less strategic. Global demand for raw rubber collapsed, and Belterra's high labor costs could not compete with Asian producers. Ford Motor Company sold the plantation to the Brazilian government, which continues to operate it today under EMBRAPA, the federal agricultural research corporation. The trees are still there, older and taller now, scattered across perhaps 10 square kilometers of working grove. The town persists, with 1,000 to 2,000 inhabitants, mostly plantation workers and their families. A 2010 census counted 16,324 people across the full district including surrounding villages. You can walk through the remaining bungalows and the water tower still stands, a Detroit skyline in miniature rising above the Tapajos forest.

Belterra's municipality includes part of the Tapajos National Forest, a 549,067-hectare sustainable-use conservation unit created in 1974. The forest is a working preserve, home to traditional communities, rubber tappers still harvesting wild latex, and research stations studying Amazonian ecology. The contrast between Ford's imported plantation and the native forest that surrounds it tells a longer story about how Amazon latex was actually produced for most of its history: not by monoculture plantations but by tappers working wild trees scattered through the forest, each one cut on its own schedule and bled by hand. That older system unravelled after 1912, when Asian plantations grown from smuggled Brazilian seed broke the Amazon's monopoly. Ford tried to replace it with industrial monoculture. The forest won. The plateau of Belterra is now one of the stranger places in the Amazon, a retired American company town slowly dissolving back into the green.