The business of housing, transporting and watching over migrant children detained along the southwest border is not a multimillion-dollar business. Its a billion-dollar one. Southwest Key Programs has won at least $955 million in federal contracts since 2015 to run shelters and provide other services to immigrant children in federal custody. Its shelter for migrant boys at a former Walmart Supercenter in South Texas has been the focus of nationwide scrutiny, but Southwest Key is but one player in the lucrative, secretive world of the migrant-shelter business. About a dozen contractors operate more than 30 facilities in Texas alone, with numerous others contracted for about 100 shelters in 16 other states. Trumps order ... calling for migrant families to be detained together likely means millions more in contracts. A small network of private prison companies already is operating family detention centers in Texas and Pennsylvania, and those facilities are likely to expand. Defense contractors and security firms are also building a presence in the system, including General Dynamics ... and MVM Inc.. In Harlingen, [Texas] one recent morning, the federal courthouse that hears immigration cases was packed. Teenagers who had been apprehended crossing the border sat in the courtrooms. In the lobby, a group of men and women ... patiently waited for the hearings to end. They were there for the migrant youth. But they were neither relatives nor lawyers. They were contractors.