Many rank and file liberals, at least if they are union members or African American, are as anti-uncontrolled large scale immigration as are conservatives. It is no coincidence that the height of trade union power (1930-1970) took place at a period of low, controlled immigration. Likewise, the great advances of the civil rights movement in the 1950s and 1960s coincided with the low levels of foreign immigration of the period. During the periods of high immigration, labor union growth was thwarted by the ready availability of scab labor, often recent immigrants. As for the blacks, their share of the labor market was lost in the Northeast first to Irish and German immigrants and then to the 1880-1920 waves of Eastern and Southern Europeans. Not until the end of large scale immigration around 1920 did African Americans escape en masse from the rural poverty and harsh and vindictive white rule of the post-Reconstruction South. The economic expansion of the 1920s and the post-World War II era offered rural Southern blacks employment opportunities in the big cities of the Northeast and the Midwest.
However, union and black leadership have essentially sold out their constituencies for the liberal supported goal of large scale immigration.