What is Zinn's main argument in Chapter 2 of A People's History of the United States?

In "Chapter Two: Drawing the Color Line," Howard Zinn seeks to find answers to two questions: where did American racism originate and what--if anything--can end it. Zinn's main argument is that American racism originated in the political, economic, and social systems the colonial elites established in America and which still, to a great extent, remain today. He explains that colonial conditions were ripe for the enslavement of the African race:

We see now a complex web of historical threads to ensnare blacks for slavery in America: the desperation of starving settlers, the special helplessness of the displaced African, the powerful incentive of profit for slave trader and planter, the temptation of superior status for poor whites, the elaborate controls against escape and rebellion, the legal and social punishment of black and white collaboration.

The colonial elites exploited these factors to their own advantage and profit, and the elites have continued to exploit them throughout the history of the United States. Zinn proposes that if the nation truly hopes to mend race relations, it must:

eliminat[e]...that class exploitation which has made poor whites desperate for small gifts of status, and has prevented that unity of black and white necessary for joint rebellion and reconstruction.

In plain terms, poor whites must recognize that their true enemy is not African-Americans, it is the powerful and wealthy elites who have used racism to distract the white lower class from recognizing the elites as the true source of their problems.