One day in 1957, a road crew pulled up to Windom Road and put a corrugated metal highway barrier sideways across the street. The barrier stopped cars from going down the road connecting two small Maryland towns just north of Washington, D.C. But it also made clear the danger for residents of the historically Black town of North Brentwood if they crossed the border into majority-white Brentwood, a “sundown town” where they would be at risk of violence after dark.