It may surprise you to learn that it has been a tradition of the Catholic Church to approve of "race mixing." Look at the racial ambiguity that we see in Latin America. This is a result of a deliberate policy of the Catholic Church. The condemnation of the segregation of the conversos in Spain. The Catholic Church traditionally has disapproved of the policy of racial segregation.

Following the cινιℓ ωαr...the Church tolerated segregation so that "Negroes could practice their Faith more freely".

http://news.google.com/newspapers?nid=1350&dat=19560220&id=4lZIAAAAIBAJ&sjid=uAAEAAAAIBAJ&pg=7353,2377185

The prohibitions of the O.T. were for the Jєωs to preserve the true religion and the pure blood-line that there be 100% proof of Our Lord's identity.  The N.T. retains one of those prohibitions, to preserve the true religion. There is no longer a spiritual  reason to prohibit race mixing.  The prohibition on marriage to those of false religion, however, remains.  As those who practice the true religion grow ever scarcer, Catholics should be proportionately more concerned with gaining true converts, and with providing young people of marriagable age with a pool of suitable candidates.  
It seems that neither is the case.  Those with the true faith spend more energy on fighting one another than on making true converts.  As for facilitating suitable partners for the young, they are too often left with the miserable choice between "conversion dating" or life-long single-hood.
Bp. W.'s point is a practical, not  spiritual.  A mixed-race couple will encounter many difficulties of a social nature, as will their children.  These difficulties are not insurrmountable, whereas the problem resulting from a marriage of mixed religion has eternal consequences.

Obviously, the roman catholic church will marry people of different races/ethnicities.  

Our cultural elites, on the other hand, seem to be enthusiastically supporting race mixing and going out of their way to condemn any discouragement of it.  I do not believe that our cultural elites can be described as anything but anti-catholic.  So, I don't think they are doing this because they believe that Christ died for all mankind.  

If two people of different races wanted to marry i don't see a legitimate reason to prevent that from happening nor shunning them. On the same note, I don't see anything wrong (given the circuмstances) to take measures that would slow the rate at which interracial relationships are occurring. This would include segregation and deportation of illegal immigrants. Segregation does not have to include outlaw of interracial marriages. Rather the right to segregate and to preserve geographical segregation. This does not inhibit a person of another race from practicing the Faith. Thus maintaining that eternal salvation is open to all of mankind. Tell me where I am wrong.

Louisiana Catholics take stance against assimilation of races in 1957...

http://news.google.com/newspapers?nid=1532&dat=19570806&id=Dbk9AAAAIBAJ&sjid=5ysMAAAAIBAJ&pg=4793,16260259

Quote from: poche

That was a reluctant toleration.

Do you have evidence of that? To me it says that segregation is tolerable under certain circuмstances.

The clue is in the words "toleration" and "tolerable".

You don't merely "tolerate" something that you think is good! Toleration is reserved for things that are not ideal.

What's wrong with racial mixing?  God approves of men and women marrying each other, and they are totally different species.