The “color line” has long served as a metaphor for the starkness of black/white relations in the United States. Yet post-1965 increases in U.S. immigration have brought millions whose ethnoracial status seems neither black nor white, boosting ethnoracial diversity and potentially changing the color line. After reviewing past and current conceptualizations of America's racial divide(s), we ask what recent trends in intermarriage and multiracial identification – both indicators of ethnoracial boundary dissolution – reveal about ethnoracial color lines in today's immigrant America. We note that rises in intermarriage and multiracial identification have emerged more strongly among Asians and Latinos than blacks and in more diverse metropolitan areas. Moreover, these tendencies are larger than would be expected based solely on shifts in the relative sizes of ethnoracial groups, suggesting that immigrationgenerated diversity is associated with cultural change that is dissolving ethnoracial barriers – but more so for immigrant groups than blacks.