The loud and uncontrollable sobs I heard from the living room in my house were jolting, especially since the sobs came from my mother. In between her sobs she kept repeating in a mantra-like trance, "He's dead, He's dead."

He was the Rev. Dr. Martin Luther King Jr. Her plaintive cry was not merely a cry of anguish from someone who had lost a cherished loved one. It symbolized the collective wail of legions of African Americans, and indeed Americans of all colors, who loved and cherished a man who had meant so much and had done so much for them. King's killing hit the collective gut of the nation. There was the gnawing sense that an era had come to a violent and crashing end with his murder.

Forty years after King was gunned down April 4 in Memphis by James Earl Ray, that sense of loss has not diminished.

Neither have the challenges that King faced, and that civil-rights leaders - Al Sharpton, Jesse Jackson, Martin Luther King III, the SCLC, and the NAACP - still face four decades after his assassination.

In King's day, things were much simpler for civil-rights leaders. Their fight was against bigoted sheriffs and mobs. Civil-rights leaders firmly staked out the moral high ground for the modern day civil-rights movement. It was classic good versus evil. The gory news scenes of baton-wielding racist Southern sheriffs, fire hoses, police dogs, and Klan violence unleashed against peaceful black protesters sickened many white Americans. All, except the most rabid racists, considered racial segregation immoral and indefensible, and the civil-rights leaders were hailed as martyrs and American heroes in the fight for justice.

Black people had the sympathy and goodwill of millions of whites, politicians and business leaders, and even a president who shouted, "We shall overcome" - the slogan of the civil-rights movement.

Those days are long gone.

Now, civil-rights leaders must confront the indifference, even outright hostility, of many white and non-white Americans to affirmative action, increased spending on social programs, and civil-rights marches.

This points to another challenge that King only began to wrestle with in his last days. That's the plight of the legions of urban black poor. As America unraveled in the 1960s in the anarchy of urban riots, campus takeovers, and antiwar street battles, the civil-rights movement and its leaders fell apart, too. Many of them fell victim to their own successes and failures. When they broke down the racially restricted doors of corporations, government agencies and universities, middle-class black people, not the poor, rushed headlong through them.

Four decades later, there are now two black Americas.

The fat, rich and comfortable black America of Oprah Winfrey, Robert Johnson, Bill Cosby, Condoleezza Rice, Denzel Washington and the legions of millionaire black athletes and entertainers, and middle-class businesspeople and professionals. They have grabbed a big slice of America's pie.

The poor black America is fragmented and politically rudderless. Lacking competitive technical skills and professional training, and shunned by many middle-class black leaders, they have been shoved even further to the outer margins of American society.

The chronic problems - gang and drug violence, family breakdown, police abuse, the soaring incarceration rate of young black males, the mounting devastation of HIV and AIDS disease in black communities, abysmally failing inner-city public schools - have made things even worse for them. The civil-rights leaders who address mostly middle-class concerns at times have seemed clueless on how to get a handle on those problems.

The furious internal fights among black people over gay marriage, abortion and immigration have tormented, perplexed and forced civil-rights leaders to confront their own gender and political biases. They have tried to strike a halting, tenuous balance between their liberalism and the social conservatism of many black people.

The weighty challenges that face today's civil-rights leaders would perplex and frustrate King if he were alive. Forty years ago, tortured sobs like my mother's over King's murder forced the nation into a deep soul search over race. It's a soul search that still goes on.