President Obama and his family celebrated Martin Luther King’s birthday by painting fruit characters on a schoolhouse wall as part of anti-obesity campaign.

Evoking King’s legacy, the president didn’t mention Memphis.

That was the slain civil rights leader’s last campaign. He went to support a hotly contested unionization effort on the behalf of the city African-American sanitation workers.

Listening to President Obama’s remarks on King’s birthday, you might think that the slain civil rights leader was mainly about encouraging volunteerism.

No doubt child nutrition is an important issue. But reducing King’s legacy to some bland notion of community service seriously understates what King, and the others who struggled alongside him, were about.

King upset people. He challenged power. He divided the country. During his lifetime, politicians demonized him. Law enforcement wiretapped and harassed him.

King, meanwhile, moved from a struggle for civil rights for minorities to a broader struggle for economic rights.

In Memphis, conflict had been building since February 1968, when two black sanitation workers were crushed to death when the compactor mechanism of their trash truck was accidentally triggered during a heavy rain.

On the same day in a separate incident also related to the bad weather, 22 black sewer workers had been sent home without pay while their white supervisors were retained for the day with pay. A couple of weeks later most of he city’s black sanitation workers began a strike for job safety, better wages and benefits, and union recognition.

The mayor, Heny Loeb, staunchly opposed the workers' demands, especially union recognition, and he resisted all efforts to resolve the strike.

King had led a march in support of the strikers in late March but he was deeply distressed when it turned violent and one man was killed. Nonetheless he returned to the city a week later to participate in another march. Several days before the march was scheduled, as King stepped out of his motel for dinner, he was assassinated.

Only after King’s death did the sanitation workers win their struggle for better working conditions and union recognition.

Is it any wonder that President, who every day binds himself more tightly to the interests of Wall Street and the Chamber of Commerce, wouldn’t want to invoke this more challenging aspect of King’s legacy?

Obama’s election can be seen as the historic culmination as just one of King’s ambitious goals. But on the road that took King to Memphis, we still have a long way to go.