[Note: This is the second article in an occasional series on the marriage revolution. Because facts and evidence are essential for making gospel-centered arguments about the cluster of controversial topics related to marriage, the first few posts attempt to clarify some of the important numbers related to marriage.]

The “marriage revolution” is an admittedly vague term for the cluster of modern phenomena related to the institution of marriage. At its core, the marriage revolution is an outgrowth and outworking of the sexual revolution, the liberalization of established social and moral attitudes toward sex, particularly in Western countries during the 1960s. Because of this connection, the beginning of the marriage revolution can also be dated to the era of the 1960s. But when did the decline of marriage begin? And how long has the rate of marriage been falling?

To answer those questions and to determine when the marriage revolution changes occurred, we need a baseline for comparison. For example, if we say that marriage rates are in decline, we need to know what marriage rates looked like in the past and how current rates compare to previous eras.

Fortunately, Randy Olson, a postdoctoral researcher at the University of Pennsylvania, has gone to the trouble of compiling the data on marriage in the United States over a period of 144 years. For decades, the Centers for Disease Control’s National Center for Health Statistics has published reports on vital statistics that include rates of marriage and divorce. Olson collected the data and put it into a spreadsheet which you can download here.

To provide a visual overview of the data set, Olson charted the per capita marriage and divorce rates and added a few annotations to denote major historical events.

(You can also find an interactive version of the per capita chart here.)

Here are a few points worth noting about the data:

• The data show the number of new marriages and divorces for each year from 1867 to 2010.

• In 1867, the population of the United States was 36.9 million; in 2011 it had grown to 312 million. By using the per capita figures, we can make apples-to-apples comparisons between years without them being becoming overly skewed by population growth.

• From 1867 to 1902, the marriage rate was essentially flat. After 1903 and until 1987, the marriage rate mostly stayed above 10 percent. (We’ll consider the outlier period from 1950 to 1970 in a moment.)

• At the beginning of America’s entry into the two global wars—WWI in 1917 and WWII in 1941—we find spikes in the marriage rates. We see similar spikes in marriage at the conclusions of those wars in 1918 and 1945.

• As Olson notes, the only notable spike in divorce rates in the past 144 years also followed the conclusion of WWII. This is likely due, he says, to “many of the pre-WWII marriages coming to an abrupt end once the romance of wartime marriage wore off.”

• The most significant drop in marriage rates prior to the 1980s occurred during the Great Depression. The hardship of that era led to a sharp 25 percent drop in marriage rates.

• One peculiar spot in the data is during the 1950s and early 1960s—a period when almost all adults in the United States were married. How do we account for the discrepancy? As Olson explains, “People weren’t marrying less in the 1950s and 1960s, but the surge of newborn children during the Baby Boom artificially decreases the per capita rates. Once the Baby Boomers came of age in the 1970s, marriage rates returned to pre-WWII levels—barring a slight drop in marriages during the dramatic conclusion of the Vietnam War (1975).” In other words, the rapid increase in children after the war skewed the population numbers, which drove down the per capita rate of marriage.

• The divorce rate remained 1 percent or less from 1867 to 1915 and remained less than 2 percent until 1940. The first year the divorce rate exceeded 3 percent was in 1969—the year California became the first state to adopt “no-fault” divorce. (No-fault divorce allows a married couple’s claim of “irreconcilable differences” as sufficient grounds to end a marriage.)

• From 1968 to 1987, the marriage rate stayed at or above 9.9 percent. It dropped to 9.7 percent in 1988 and 1989, climbed back to 9.8 percent in 1990, and dropped steadily until 2009, where it remained at 6.8 percent.

• The divorce rate peaked between 1979 and 1981 at 5.3 percent. Since then the divorce rate has steadily declined along with the rate of marriage.

Now that we’ve explored the data, what year should we use as the marker for the beginning of the decline of marriage in the United States? I would argue for 1985, the last year that the marriage rate topped 10 percent. In only two years since then has the rate reversed course and increased more than the previous year (from 9.7 in 1989 to 9.8 in 1990 and 8.1 in 1998 to 8.4 in 1999). But both of those year-to-year increases were immediately followed by nearly decade long declines. The year 1985 may also mark the last year that America ever sees a marriage rate of more than 10 percent.

What changed in 1985 that could have led to the decline in marriage? There are likely numerous factors—which we’ll examine in future articles—but one stands out in particular: By 1985, all states (except for New York) had enacted no-fault divorce legislation. (New York didn't adopt no-fault divorce until 2010.)

In the next article in this series we’ll examine the historical changes in divorce laws and consider how they might have led to the overall decline in marriage as an institution.

Other posts in this series:

• Is There Any Actual Demand for Same-Sex Marriage?