Clotheslines with billowing linens and long dresses are a common sight on the off-grid farms of Pennsylvania’s Lancaster County, home to the nation’s largest Amish settlement. For many tourists they’re as iconic a part of Amish Country’s bucolic scenery as the rural lanes and wooden bridges. But for two days in late April, a clothesline with a different purpose was strung in a small indoor exhibit here. Hanging from it were 13 outfits representing the trauma of sexual assault suffered by members of the Amish, Mennonite and similar groups, a reminder that the modest attire they require, particularly of women...