As Americans wed less frequently and for fewer years, retirement security for black women is taking the biggest hit, according to a study released Wednesday by the General Accountability Office, the investigative arm of Congress.

The percentage of black women age 50 to 59 who could not receive Social Security spousal benefits in 2009, either because they had never been married or they had been married for less than 10 years (the eligibility minimum) was more than double the rate for all women. Between 1990 and 2009, the ineligibility rate for women of color soared from 13 percent to 34 percent.

In the years ahead, the race gap is projected to widen. By 2040, the proportion of widows to receive “dually entitled” benefits as a result of work and marriage is projected to increase by 12 percent, yet African-American widows will see a 35 percent decrease.

Overall, the proportion of women ineligible for Social Security spousal benefits because they never married is expected to more than double in the coming years, according to the report. Four percent of women born between 1936 and 1945, it’s projected, will have not married by age 70. That number is expected to leap to 10 percent among women born from 1966 to 1975.

Married couples likely have more in savings than single women, said the report. In 2010, 71 percent of married couples age 50 to 64 had retirement savings, while only 48 percent of households headed by a single woman did.

The couples had on average $122,560 in savings while single women held a bit more than 25% of that, $32,800.