Money can't buy happiness, the old adage says. But maybe combining it with marriage can help.

Why it matters: Marital status is a stronger predictor of American adult wellbeing than education, race, age and gender, according to newly released data from the Institute for Family Studies and Gallup.

• Last year, married adults between 25 and 50 years old were 17 percentage points more likely to be thriving than adults who never married.
• Household income adjustment has the biggest sway on wellbeing for individuals, and typically rises after marriage when a couple pools their resources.

The intrigue: Demographic differences don't explain the higher prevalence of happiness across relationship status, the research found.

• Married women and men both see a 20-percentage-point advantage compared to unmarried same-sex peers.
• "A married adult who did not attend high school evaluates life higher, on average, than an unmarried adult with a graduate degree, after adjusting for gender, race, and age," the report said.

Zoom out: Americans are forgoing or delaying marriage.

• The marriage rate over the last 50 years dropped by nearly 60%, and divorce is now more widely accepted in the U.S.
• Separately, more Americans are living alone, as the country faces an isolation and loneliness crisis.

Between the lines: Marriage, as an institution or relationship, isn't necessarily the source of happiness.

• People with character attributes linked to happiness, like agreeableness, emotional stability and conscientiousness, may be more likely to seek out marriage, according to Gallup.
• Even when controlling for household income, "married people remain significantly more likely to be thriving," the report said.

Go deeper:

• America the single
• Divorce in America gets a glow up