Open borders will mean lower wages for American workers.

The American Prospect reports:

In a 2014 survey, sociologist Stephen Steinberg concluded that legal and illegal immigration had damaged opportunities for African Americans “in construction, light manufacturing, building maintenance, the hotel and leisure industry, the health care industry, and even public-sector jobs where one-third of blacks are employed.”

In 2010, the U.S. Civil Rights Commission issued a report on “The Impact of Illegal Immigration on the Wages and Employment Opportunities of Black Workers.” It concluded that “illegal immigration to the United States in recent decades has tended to depress both wages and employment rates for low-skilled American citizens, a disproportionate number of whom are black men.” As Steinberg notes, one of the great ironies of our recent history is that immigration policy, which was partly inspired by the civil rights movement, has probably had a negative effect on African Americans at a time when African Americans might have been able to take advantage of the passage of civil rights acts outlawing employment discrimination.

Even the leftist American Prospect admits open borders isn't a great thing.