In rural Pike County, Illinois, a solitary highway marker surrounded by mown grass, potted flowers and a small American flag stands by a little-traveled road. "SITE OF NEW PHILADELPHIA," it reads. Beyond the marker stretch cornfields, trees and gentle hills as far as the eye can see. The vista hasn't changed much since "Free Frank" McWorter, a former slave, moved his family here in 1831 and later started the town, the first in America legally founded by a black person.

McWorter dreamed big. New Philadelphia's Main Street and Broadway were some 80 feet wide—broader than many streets in New York City then. By 1865, the village, likely named for the most active urban center for free blacks at the time, had become a minor commercial hub with 104 white and 56 black inhabitants. Rare in frontier America, blacks and whites went to school together and even intermarried.

Today, New Philadelphia isn't even a ghost town. The original buildings have long since been plowed under, and Broadway and Main Street are part of a gravel driveway that leads to a farmhouse. But the western Illinois town is coming back to life. Archaeologists and college students from around the country embarked this past summer on a planned three-year study, combing fields for remnants of the vanished community. "Archaeologists who study African-American history have spent most of their time excavating slave quarters," says Paul Shackel, an anthropologist at the University of Maryland, who is leading the study. "By excavating a free community in which blacks lived before the Civil War, we are breaking into a new genre."

McWorter had been a slave in Kentucky before he bought his freedom in 1819 at age 42 by manufacturing and selling saltpeter. He purchased New Philadelphia from the federal government with profits from farming. It was an investment in his family's freedom. Over the course of 40 years, he earned enough from farming and selling land to buy 16 family members out of slavery for a total of $14,000 (more than a quarter of a million dollars in today's currency). Some of his neighbors, such as farmer and fellow property owner John Walker, were also former slaves who purchased their freedom. Others, particularly after the Civil War, had fewer means: William Butler, freed by Abraham Lincoln's Emancipation Proclamation, arrived in New Philadelphia with nothing but a mule, was given a job by McWorter's son Solomon and, eventually, was able to buy land on the north side of town.

Archaeologists are filling in missing details of how and where the settlers lived. This past May, Michael Hargrave of the U.S. Army Corps of Engineers surveyed part of the 42-acre town site with a device that uses ground-penetrating electrical and magnetic fields to detect buried objects. From the radar-like images, archaeologists pinpointed 19 promising places to dig, including what was most likely a cellar or a garbage pit in the Butler home.

Twelve students spent five weeks in the field excavating 19 shallow 5-foot by 5-foot exploratory pits in recently plowed (but unplanted) fields covered by high grass. They ate lunches donated by merchants in nearby Barry, Illinois, and stayed in steeply discounted rooms at a nearby hunting lodge. "I've told them that archaeologists never have it so good," says Shackel, a genial, well-tanned 45-year-old who has worked for the National Park Service at Harpers Ferry, West Virginia, and other sites.

Shackel and his team spent another five weeks cataloging their finds, at the Illinois State Museum in Springfield. Every item had to be cleaned, placed in a plastic bag and entered into logbooks. If it was a piece of a bottle, the students would note the kind of glass; if it was a bone, they would figure out the animal it came from and the body part. If it was a piece of ceramic, they licked it. "If it sticks to your tongue, it's earthenware," explains Charlotte King, a research associate at the University of Maryland who supervised the cataloging. "Earthenware is fired at a lower rate, and so it's very porous. Stoneware is less porous, and porcelain is the least porous because it's fired at a very high temperature."

Among the 3,000 artifacts the team unearthed were shards of glass, pieces of brick, buttons, clay marbles and a dizzying variety of bones—most of them from the Butler residence. A small badge inscribed "Illinois State Fair 1903" probably comes from a long-ago prize ribbon, says King. A fragment of green glass matches a type of bottle manufactured between 1855 and 1873, probably in Louisville—which may establish a date of occupation and a possible travel route. One piece of property, just off Broadway, is recorded as "unimproved" on 1867 tax records, but tests of 40 ceramic fragments suggest that someone lived there before 1860.

So far, the materials dug up by Shackel and co-workers haven't shed any new light on the town's race relations. But documents from McWorter's time show there was plenty of prejudice in this corner of Illinois. In 1871 former Pike County resident John Hay (Abraham Lincoln's personal secretary) wrote a series of poems called the Pike County Ballads. One tells the story of "Banty Tim," who is about to be run out of town by "The White Man's Committee of Spunky Point." The poem's narrator, Sgt. Tilmon Joy, saves the day by recounting how Banty Tim saved his life at Vicksburg, and continues: "Ef one of you tetches the boy, / He kin check his trunks to a warmer clime / Than he'll find in Illanoy."

Another kind of white man's committee may in fact have doomed New Philadelphia. In 1869, the Hannibal and Naples Railroad, which was planned and paid for by white businessmen, bypassed the town. The railroad connects nearby New Salem and Barry, and a straight line would have taken the train right by New Philadelphia, but instead the track makes an inexplicable bend to the north. There's no documentary evidence that the railroad deliberately avoided New Philadelphia, but by 1872 the detour had "greatly ruined its trade," the Atlas Map of Pike County reported, and in 1885 most of the town legally reverted to farmland. A few families remained well into the 20th century. In 1936, the New Philadelphia schoolhouse finally closed its doors.

Some newspaper reports about the dig have played up the idea of the town as an oasis of racial tolerance. But a descendant of the town's founder disputes that view. The "premise that New Philadelphia was a town where blacks and whites lived in racial harmony ...is just not historic reality, any more than to claim that slaves lived happily on plantations," argues Juliet Walker, a great-great-granddaughter of McWorter and a historian at the University of Texas at Austin.

Shackel denies any attempt to idealize the past. "While the archaeology will probably not be able to show harmony or disharmony, it can illustrate the way of life for groups of people living in a biracial community," he says. "Archaeology is a way to provide a story of a people who have not been traditionally recorded in history. Our goal is to tell the story of New Philadelphia from the bottom up and provide an inclusive story of the town."

Despite their disagreements, both Walker and Shackel would like to see New Philadelphia commemorated by more than a roadside plaque. Walker envisions rebuilding the town. Shackel, who has the support of the New Philadelphia Association, a local citizens' group, hopes to turn the site into a state or national park. "There’s probably 20 years of archaeology to explore and interpret," Shackel says. "We're in the first mile of a marathon."