Final answer:
The most significant change in older adults' marital status from 1970 to 2015 is an increase in the proportion of those who have never married, due to evolving societal norms and changing priorities such as career and education over marriage.
Step-by-step explanation:
The greatest change in older adults' marital status is that they are more likely to be never married in 2015 than they were in 1970. This trend is reflected in U.S. Census data, which indicates a shift in the societal norms and behaviors related to marriage. Factors contributing to this shift include increased acceptance of single parenting and cohabitation, greater emphasis on individual education and career development, and changing cultural attitudes towards marriage.
As societal attitudes have changed, the pressure to marry has decreased and individuals are choosing to delay marriage or forgo it entirely. The median age of first marriage has increased for both men and women, signifying changing priorities and lifestyles. Even though marriage continues to be a significant institution, its patterns are evolving as people adopt new forms of relationships and family structures.