Stereotyped beliefs began to escalate about the mulattos as never before, the analogy to the mule, for example, received much attention.  Many of the same white men who fought to protect white women, helped to mold the Jim Crow practice of sexually exploiting black females by white males, which contributed to the miscegenation they were so vehemently fighting against.  By reinforcing the one drop rule, as had been done on the plantation, they defined mixed children born to black women as black.

With the passing of the post Reconstruction laws on racial intermarriage, pressure was put on the state legislatures to define what constituted being a "Negro."  Louisiana courts usually defined "persons of color" to mean those who are visible black, and many mixed people continued to go around being defined as white.  Fourteen of the remaining Southern states adopted the one-drop rule as a definition of what a Negro was; anyone of black ancestry.  In 1910 Virginia abandoned the one-fourth rule and finally settle for the one-sixteenth, which assumed that lesser amounts could not be detected.  Not until the 1930's did Virginia adopt the one-drop rule, which said that "any Negro blood at all" makes a person black.
 
Centuries on miscegenation had produced large populations of mulattos who appeared to be white and who passed whenever they wanted to.  Passing white promised a better job, and some who passed white on the job live a black life at home.  Some lived in the North as white part of the year and then in the South as black the rest of the year.  Men passed more often then women.  Some mulattos passed by taking Latin American names and moving to the appropriate location.  But the vast majority of the black population would not pass on a permanent basis due to family separation, fear of whites, condemnation from the black community which would lead to a loss of the security of the black community.
 
 During the Jim Crow laws era, black throughout the North and South shared the belief that black-white sexual contact with each other occurred only with the irresponsible underclass of both groups.  Even the black scholar, Carter Woodson said that only the weaker members of both races, ethically or biologically, engaged in such acts of miscegenation.  A popular belief spread through the black population that the mixing of whites with blacks lead to an alleged weakness which produced a certain "high" yellow color-thus called the "yellow niggers."  Lighter mulattos were considered to more preferred among white urban owners of theaters and nightclubs, which allowed the lighter mulatto girls as chorus girls, singers, and even prostitutes.  Soon the lighter mulattos began to be associated with sin and degradation.  Many in the black community became worried about lightness as white were about blackness. (excerpts taken from: Who Is Black?  F. James Davis)