Factors that lead to people living by themselves include delaying marriage in one’s youth; permanently separating or getting a divorce; living longer as a widow or widower; and never marrying, researchers say.

Single living was once fairly uncommon — only 13 percent of U.S. homes had single householders in 1960, the bureau noted in its new report, “America’s Families and Living Arrangements: 2010.”

But over the decades, the number of one-person homes more than doubled and now 27 percent of U.S. households are “just me” homes.