We are halfway through “Unmarried and Single Americans Week,” noting that many who are unmarried do not identify with the world “single,” since they may be parents, have partners, or are widowed or divorced. The idea for the observance started in Ohio in the 1980s. There are 105 million unmarried adult Americans, more than 44 percent of all U.S. residents 18 and older. Eighteen million of them are seniors over the age of 65. The number of people who live by themselves is 34 million — 27 percent of all U.S. households, a figure which in 1970 was just 17 percent. That leaves room for households with unmarried couples, of which there were 7 million in the year 2012, including nearly 640,000 same-sex households. Profile America is in its17th year as a public service of the U.S. Census Bureau.