Editor's note: This is part three of a three-part series investigating issues currently surrounding marriage in America.

The fetching images on HBO's "Sex and the City," the scores of urban playgrounds for swinging singles and the "alternative lifestyles" that just decades ago were labeled spinsterish — or worse, criminal — may all convey that singledom's time has arrived, but Tom Coleman (search) says unmarried America has a long way to go.

An avowed single and civil rights attorney, Coleman says pensions, taxes, health care benefits (search) and other economic privileges all skew in favor of married Americans and against a growing majority of untethered individuals.

"Part of the problem we have is, not only married people and people in power don’t understand these issues and inequities, but single people themselves take it for granted that that's the way it is," said Coleman, who has made it his crusade since the 1970s to defend the rights of the unmarried and unattached.

In the beginning, Coleman defended heterosexual couples from then-existing laws that made sex between two consenting but unmarried adults illegal. Much has changed since then, as the percentage of married households has plummeted 30 percent since 1950 while households with unmarried partners has climbed from 523,000 in 1970 to nearly 4.9 million in 2000.

That number doesn't even include the nearly 595,000 same-sex partners sharing households in 2000, according to the U.S. census (search).

Data suggest that men and women are waiting longer, if at all, to get married. The percentage of married white women declined from 67 percent in 1950 to 57 percent in 2000. The percentage of married black women fell further, from 62 percent to 36 percent. In 2000, 73 percent of all American women in their early 20s had not yet married compared with 36 percent in 1970.

Overall, married couples currently account for 50 percent of U.S. households. That leaves a lot of single people and cohabitating adults throughout the country — about 86 million, based on census figures.

"We are close to being an unmarried nation," Coleman said.

Some experts say the news is not good for society or for individuals who want eventually to settle down and raise a family. According to the Center for Law and Social Policy (search), children raised in healthy, married households are better adjusted both socially and economically than their peers in unmarried homes or living with single parents.

"[A divorced household] is the worst place for a child to grow up," said Mike McManus, who founded Marriage Savers with his wife Harriet in 1996, and takes credit for helping reduce the divorce rate in 122 counties through the group's Community Marriage Policy mentoring program.

"What we need to do is make marriage more attractive and help couples in cohabitating relationships to start thinking of the 'M'-word," he said.

Of course, not everyone who cohabitates could live in a legal marriage. Gay and lesbian couples live together openly, but aside from civil union laws in Vermont granting them state benefits and civil rights protections, same-sex couples cannot legally marry anywhere in the United States. The Massachusetts Supreme Judicial Court ruled Tuesday that the state Legislature needs to determine within 180 days whether to grant that right to gay couples.

Responding to the reduction in married couples, 10 states and 161 local governments now offer some sort of employee protections and benefits — from basic bereavement rights to full health insurance coverage — to unmarried domestic partners, some only to same-sex couples, others to both same and opposite-sex couples. Currently, 194 colleges and universities and over 5,500 private companies extend similar benefits to their employees.

But Coleman said a number of areas remain where unmarried people — either unattached or cohabitating — get the short end of the stick. He noted that many employees in traditional company pension plans are permitted to leave their monthly checks only to a spouse if they die before they retire. Many widows and widowers receiving spousal benefits will lose those benefits if they choose to remarry.

Singles get smaller capital gains breaks when they sell a house than married couples, and spouses don’t get taxed on inherited estates. Also, according to Coleman, married persons get paid more on average for the same job during the same length of service when spousal health benefits are factored in.

"We need to encourage employers to create single family workplaces, provide cafeteria-style benefits," he said. Under such a plan, health care money not used for a spouse or child "could go toward an elderly parent, or maybe [toward] putting a domestic partner on the plan."

William Doherty, a professor of family social science at the University of Minnesota, said the complaints sound a bit foolish and selfish.

"The single person in the workplace is resenting the fact a parent gets time off to tend to a sick child. Give me a break," he said.

Doherty pointed out that single people are typically less healthy, tend to drink more and get into more car accidents.

"Somebody could come back and say singles need to pay more into health care," he said. "These folks should be careful of how much they want to push this."

And not all financial pros and cons of marriage are cut and dry, said Pete Sepp, a spokesman for the National Taxpayers Union.

He said the so-called marriage penalty tax cut has been repealed only until 2005 and only for couples making less than $114,651 combined. Any income higher than that gets whacked with taxes.

In addition, only couples making less than a combined $110,000 can qualify for the earned income child tax credit. In both cases, Sepp said it's financially smarter for singles and non-married couples to file individually.

"There really aren't many clear indicators of tax benefits for getting married versus staying single," said Sepp.

Coleman said he wants to guarantee that eventually there are no differences.

"We need to treat everyone equally," he said.

But Doherty said not all relationships should be treated equally under the law.

Marriage is not a lifestyle choice, but a "public commodity," critical for the survival of the human race, he said, adding that it deserves special supports and incentives.

"If there is no next generation, we are gone, we are dead," he said.