The Census Bureau recently announced plans to remove from its annual American Community Survey several questions about respondents’ marital history. To non-experts, that may sound like an insignificant change to an irrelevant study—but according to scholars who study marriage and divorce, it’s actually a big deal.

To back up a bit, the American Community Survey is conducted every year on a randomly selected sample of U.S. households. In addition to the basic questions that appear in the decennial Census, the ACS includes questions about income, housing, education, military service, health conditions and insurance, employment, transportation, and more.

In 2008, the ACS began asking questions about marital history in order to remedy a long-standing lack of reliable data on that subject, a lack that, to make a long story short, resulted in part from the federal government’s decision in the 1990s to stop paying states to collect detailed data from marriage and divorce certificates each year. Specifically, after inquiring about each household member’s current marital status, the ACS asks: “In the past 12 months, did this person get a) married? b) widowed? c) divorced?” “How many times has this person been married?” and “In what year did this person last get married?”

These five questions allow the government to project future spending on Social Security and other entitlement programs, analyze how various policies and programs affect married and unmarried couples differently, and investigate how marital status and history relate to other measures such as the birth rate and infant mortality. Scholars use the same questions to calculate age-specific marriage and divorce rates, observe trends in those rates over time, study remarriage and blended families, and explore connections between family structure and poverty, education level, and more. It is these questions that the Census is now considering removing.

Steven Ruggles, who directs the Minnesota Population Center at the University of Minnesota and is President-Elect of the Population Association of America, has used ACS data in a major study of American divorce rates that he coauthored with Sheela Kennedy, and underlines how significant the removal of the marital history questions would be. Since states ceased collecting thorough data from marriage and divorce records, he explains, “we’ve been kind of flying blind.” Alternate sources of information, such as the Survey of Income and Program Participation and the National Survey of Family Growth, have major flaws, so without the ACS questions on marital history, “we’d be the only industrial country in the world that can’t measure age-specific marriage and divorce rates.” And without those numbers, we wouldn’t be able to track family trends accurately even as (in his words) “marriage is changing more rapidly than at any time in history.”

Shoshana Grossbard, a San Diego State University economics professor and founding editor of the Review of Economics of the Household, echoed Ruggles’s view about the need for precise data on marriage trends. “Marriage is an important institution, and whether people were married or divorced in the past can make a big difference in their lives, their children’s lives, and the lives of others who are connected to them. Social scientists need the information on marital history to better understand human behavior, especially in matters with policy implications such as poverty and inequality.”

The policy implications of family trends will doubtless always be contested, but presumably all sides can agree on the need to measure those trends accurately. If the Census Bureau implements its proposal to stop asking Americans about their marital history, doing so will become much harder.

To comment on the proposed change, visit this page.