The land is cheaper, it's less densely populated. In a broader rural landscape, we're having the whole frontera go through what the inner cities did in the nineteenth century. Most of the immigration has been urban. This is rural. The prices are attractive to low-income workers, who have to pay up to four times the amount for a comparable piece of land in, say, Ciudad Juarez, Mexico, a short jaunt down the highway.
Land is actually cheaper in southern New Mexico than in many parts of Mexico.
After buying their plots, residents install trailers or build new houses, often constructed brick by brick over a period of time as the owners save enough money to buy the building supplies. Not everyone welcomes the settlements, however. In Hatch, residents tried to halt the spread of colonia dwellings on the edge of town. Three years ago, the village threatened to evict some colonia homeowners after passing an ordinance restricting the establishment of trailer homes. But the inhabitants fought back with a lawsuit alleging racial discrimination.