PORTLAND, Maine — Moses Samuel Green was born a slave in Maryland in 1853. He died a free man in Maine, 89 years later. When they laid him to rest in 1942, Green was one of the wealthiest African Americans in town. By day, he ran a shoeshine stand at Union Station — but he made his fortune in his off hours, away from the trains. In the process, Green helped countless people find homes in a city where racism sometimes made it difficult for African-Americans to find a place to live.