This weekend, thousands of lesbian, gay, bisexual, and transgender Americans will march in the nation's capital. They won't be marching for marriage rights alone. They'll be marching for complete federal equality - an end to second-class citizenship.

Organizer Cleve Jones sees Sunday's National Equality March as introducing a shift in movement strategy, from an emphasis on the patchwork progress made in states and localities to an unqualified demand for national equality. Such a move would hold the federal government more accountable not only for its current policies - some of which, such as the Defense of Marriage Act, interfere with progress on the state and local levels - but for its long history of anti-gay discrimination.

Few realize how long that history actually is, but federal hostility to homosexuality is at least a century old. Indeed, 2009 can be considered a centennial that offers another reason to march: 100 years have passed since federal officials first began to build a citizenship policy that excludes or degrades gay, lesbian, bisexual, and transgender people.

In 1909, an immigration official named Marcus Braun sat down to type out a report warning of a "new species of undesirable alien" who he believed should be barred from entering the country: "the moral degenerate," or homosexual. The Braun report was a quiet, bureaucratic start, but it represents nothing less than the beginning of gay and lesbian expulsion from the rights and obligations of national citizenship.

After Braun stood up from his typewriter, the architecture of second-class citizenship for homosexuals was gradually constructed across the federal bureaucracy. By the middle of the 20th century, the U.S. government had distinguished itself from other Western democracies in its hostility to homosexuality.

Homosexual aliens were explicitly prohibited from entering the country and from naturalization. They were barred from serving in the military and fired from jobs in the civil service. Washington even tried to steer government benefits away from homosexuals by reserving the most generous benefits for married couples and by excluding homosexuals from programs such as the GI Bill.

And while states and localities generally policed homosexual conduct, the federal government often went beyond the issue of conduct to police homosexual status or personhood. To do so, federal officials used ill-defined and ambiguous concepts. The military's historical policy on homosexual tendencies, for example, punished the homosexual, as one man put it, "less for what he does than for who he is."

Once in place, federal exclusion has proven remarkably durable. Today, only its sharpest edges have been blunted.

The ban on gay federal employees has been lifted, but the community still has no umbrella of protection against employment discrimination comparable to that of the 1964 Civil Rights Act. Congress ended its restriction on gay immigrants in 1990, but gays and lesbians cannot secure legal residency for their same-sex partners through marriage, as straight people can. The prohibition against openly gay personnel in the armed services is still in place. And Social Security and other federal benefits do not extend equally to gays, who are ineligible to receive benefits accrued by a life partner upon his or her death.

Furthermore, the 1996 enactment of the Defense of Marriage Act demonstrated that the federal government's backwardness goes beyond perpetuating retrograde policies to actually inaugurating new ones.

This is, of course, why gay activists have for so long directed their efforts toward making change at the state and local levels; that has simply seemed to be the best use of their time. Their victories there have been nothing short of astonishing. Gay marriage is now legal in six states, and many more have laws prohibiting discrimination on the basis of sexual orientation or gender identity in housing, employment, and other areas.

I hope we not only continue to "fill in the map" on those issues, but also build on momentum coming out of the states to demand more change at the national level. My reasons for this are grounded less in contemporary political calculations than in the history of national citizenship, including this unhappy centennial for lesbian, gay, bisexual, and transgender Americans. We merit the attention of federal policy makers - and our issues are not merely state and local matters - because of this long period during which the federal government has been not just an inadequate protector, but a key inflicter of our pain.

Consider the words of one young soldier accused of homosexuality who found herself in front of a military board facing an undesirable discharge. "I don't feel that I am being treated like an American citizen," she said. "I would like to know why."

The year was 1958, and this brave woman did not need the experience of 100 years of federal discrimination to motivate her very simple question. How many more years do we need to answer it?