When citizens in Maryland, Maine, Washington, and Minnesota go to the polls in November, they will be confronted with ballot initiatives that speak to the central question of what marriage is.

In Minnesota, voters will consider whether to amend their state constitution to preserve the definition of marriage between one man and one woman consistent with state statutory law. Voters in Maryland and Washington will weigh referenda asking whether they wish to ratify same-sex marriage measures adopted by their state legislatures and signed into law earlier this year. In Maine, voters will consider a ballot initiative to issue marriage licenses to same-sex couples and render gender-neutral any terms in the state’s laws relating to marital and familial relationships.

To date, the voters of 32 states have weighed in on these new questions about marriage’s definition, and in each, they have chosen to protect marriage as the union of husband and wife. The most recent to do so was North Carolina, whose citizens voted 61 percent to 39 percent to adopt a constitutional amendment affirming the traditional definition of marriage.

These developments have been occurring against the backdrop of a rapidly changing political and legal environment regarding marriage. Following North Carolina’s historic vote, the President of the United States announced his “evolution” on marriage, reversing his earlier position that it is between one man and one woman.

Meanwhile, California’s successful marriage ballot initiative, Proposition 8, was challenged and struck down in federal court. Earlier this week, Proposition 8’s supporters asked the Supreme Court to review the case, and observers predict that it is likely to do so in its next term. The Court has also been asked to hear multiple cases regarding the Defense of Marriage Act’s definition of marriage. And earlier this week, the Democratic Party appeared poised to embrace same-sex marriage in its party platform.

This is a seminal moment for the institution of marriage—whose definition is deeply rooted in what Americans have long understood the institution’s central characteristics and public purposes to be.

As the building block for the rest of society, marriage’s central civic purpose has always been to connect biological parents—especially fathers—to their children. Its meaning is integrally linked to the social needs it is designed to address.

As Brian Brown of the National Organization for Marriage Education Fund argued at a Heritage event discussing the four ballot initiatives on Tuesday:

[I]t is rational to believe…that marriage is by definition, by objective reality, the union of one man and one woman…. [T]his relationship we call marriage is different than any other relationship because of the interest that the state has in children. This is the relationship by which children are brought into the world and connected with their biological mother and father, and societies have to have that.

These “fundamental realities,” as Brown described them, are at the heart of the marriage questions before Americans today—most immediately, those in Washington, Minnesota, Maryland, and Maine.