In New York City, even sidewalk space is coveted real estate. Street vendors sometimes spend a fortune or languish for years on waiting lists to acquire one of the permits that allow them to sell goods in tightly regulated locations. But once a year, there's an exception, laid out in an artfully worded city ordinance: During the month of December, anyone may sell "coniferous trees" just about anywhere - no license required. It's a rare tree-for-all. Peddlers flock in from across North America. Big trucks carrying huge loads of trees arrive in the dead of night. Stands selling coniferous trees...