Final answer:
The Baby Boomers, born between 1946 and 1964, represent the largest single age group in the United States, and by 2030, all will be aged 65 and older.
Step-by-step explanation:
The cohort that represents the largest single age group in the United States is the Baby Boomers. Born between 1946 and 1964, the Baby Boomers were part of a dramatic increase in births known as the baby boom. As this generation has aged, they have consistently represented the largest segments within the U.S. population. In 2000, they were the bulk of the age group from thirty-five to fifty-five. By 2010, the then oldest Baby Boomers had started to reach what is considered elderly age by the U.S. Census, pushing the largest group to those aged forty-five to sixty-five. By 2030, all Baby Boomers will have reached the age of 65 or older, significantly influencing the demographic profile of the nation with a larger portion of the population being elderly.