There is apparently a thriving black market for baby red-eared slider turtles in Baltimore. The sale (and possession) of small turtles is illegal in Maryland, like many other regions, largely because of public health concerns regarding Salmonella.
Over 100 hatchling turtles have been seized in the past 2 weeks. Baby turtles offer a good profit margin for black market vendors. They can be purchased from farms in the southern US for about $1 each and then resold for many times that amount. One person was caught selling turtles out of the back of a van. (Why anyone would buy anything from someone selling out of the back of a van is beyond me!)
People buy turtles thinking they make cute pets, not realizing what they need to do to keep them healthy as they grow. Turtles that are fortunate enough to be raised properly create another problem, since most people are not willing or able to take care of adult turtles that reach 10-12 inches in length. This can result in turtles being killed or abandoned.
Another major problem in the risk of Salmonella. Turtles very commonly carry this potentially harmful bacterium, and they are an important source of infection in people. The concerns are greatest with young children who may handle small turtles and put them in their mouths. People need to think before they buy. Before getting any pet, learn about the animal, including requirements for care and human health risks (and also if it's legal). A little common sense goes a long way.
More information about Salmonella and turtles can be found on the Worms & Germs Resources page.