Modern family structures in the past and present vary from what was typical of the 1950s nuclear family. The families of the second half of the 19th century and early 20th century in the United States were characterized by the death of one or both parents for many American children. In 1985, the United States is estimated to have been home to approximately 2.5 million post-divorce, stepfamily households containing children. During the late 80s, almost 20% of families with children headed by a married couple were stepfamilies.