The most common types of rats found throughout the United States are Norway rats and roof rats. Both rodents belong to the genus Rattus and can be found anywhere human populations thrive. These rats are similar in size and appearance and enter buildings looking for food or to escape cold weather. Inside, they contribute to structural damage and the spread of disease. One of the main differences between Norway and roof rats is where they're found in homes. Roof rats get their name from their tendency to enter structures in elevated spaces, including attics and ceilings. In contrast, Norway rats are found along building foundations, woodpiles, and in basements. Other Rats and Their Diseases Other rodents commonly associated with rats despite their difference in scientific classification include rice rats, cotton rats, and pack rats. Cotton rats and rice rats are considered dangerous to humans because they carry strains of Hantavirus. A severe, sometimes fatal disease, Hantavirus Pulmonary Syndrome is a respiratory ailment found in the feces, urine, and saliva of infected rodents. People can contract the disease simply by breathing in air contaminated with rodent droppings, being bitten by an infected rat, or eating and drinking substances tainted with the virus. Finally, pack rats, also called wood rats, are common in various areas of the United States. They grow up to 17 inches in length and are notable for having furry tails shorter than the length of their bodies. Along with transmitting diseases, pack rats damage garden crops.