A baby born some time this October will be the 300-millionth American, but he or she shouldn’t expect a house full of siblings. The average number of people living in U.S. households has dropped almost one whole body each time the country adds 100 million citizens, according to the U.S. Census Bureau. When the 300-million milestone is reached, that number will be at a new low of 2.6 people per home-parents, offspring and extended squatters included. A combination of cultural factors is behind the shrinking American household, experts say. ‘It’s the three Fs-family, freedom, and finance,’ said Gil Troy, professor of American history at McGill University in Montreal. Goodbye Ozzie and Harriet When the U.S. population reached 100 million in 1915, the average number of people sharing a home was 4.5. Larger, patchwork families were just more common back then, say historians. ‘In 1915, you might have had Granny and Gramps living [at home] as well as more little’uns scampering about,’ Troy told LiveScience in a recent email interview. With the advent of better transportation and looser social restrictions in the years that followed, people were able to leave the nest, Troy […]