The North Korea Human Rights Act of 2004 cleared the way for North Koreans to immigrate to the U.S. Before that they were recognized as South Koreas and fell under those immigration regulations. Apparently, U.S. immigration law has recently been amended as well:

The U.S. government has added North Korea and Burma to the list of nations covered by “Priority 3,” meaning that nationals from those countries with family members in the United States would be given priority screening… Defectors already resettled in third countries like South Korea are excluded from possible refugee status.

However,

Under the U.S. refugee program, Priority 3 applies to people who are spouses, unmarried children or parents of persons admitted to the U.S. as refugees or granted asylum.

So it is unlikely that many North Koreans will be able to take advantage of that regulation – at least for the time being.

Former North Koreans living in South Korea, however, may try to begin immigration to the U.S., as they most generally do not integrate well into the South:

In their homeland, they are blacklisted as “traitors” who must be caught and punished, often in labor camps. In the South, once welcomed with huge cash gifts and news conferences, these people now tend to be considered a burden on the government budget, a political nuisance or simply ill-trained alien workers whose rigid socialist manners often conjure more bewilderment than sympathy. Surrounded by more affluence than they had ever imagined yet becoming alienated in the South, they live in constant fear over the fate of their relatives in the North.

While being permanently relegated to menial positions depressing for many North Koreans, they find the antiquated South Korean family register system to be an equally frustrating buerocratic hurdle to the ‘pursuit of happiness’:

There has not been much change in the type of legal problems since the legal consultation assistance program started in 2003, and it seems as though the North Korean defectors are most suffering from family problems after resettling in South Korea… Although in Seoul Family Court of Justice, there have been 163 divorce lawsuits filed until this March, but no case had been processed after the only and the last divorce permitted in February last year. Because North Koreans are unfamiliar with South Korean legal process of the civil affairs, criminal cases, and administrative affairs, face much difficulty…

Looking to and past reunification, this could lead to the U.S. being a preferred immigration destination over South Korea for former North Koreas, although China is apt to be popular as well.

UPDATE: It’s not the U.S., but see the JoongAng Ilbo for, “North Korean is granted refugee status in Mexico.”