There is a shadow population among the estimated 14,000 homeless who live on Skid Row. A growing number of immigrants are bedding down each night in parks, abandoned buildings and cardboard boxes, finding refuge in camouflaged encampments under freeway overpasses and bridges. Mostly from Mexico and Central America, many entered the United States illegally in search of a steady job - and fell far short. They largely shun the free meals and beds offered on Skid Row, and according to service providers are less likely to be drug addicted or mentally disturbed than other homeless in the destitute area on...