Several studies indicate that there is roughly one rat for every person in the United States, and the ratio is similar in other nations. A study conducted in the United Kingdom in 1909 indicated a similar ratio, although the results of that study have been periodically challenged. Many of the 56 species of rats live in the wild and do not tend to thrive in areas inhabited by humans.
More facts about rats:
- New York is considered one of the more rat-infested locations in the United States, with rats thriving in sewers, subways and other areas of the city. Several studies indicate a one-rat-per-person ratio there, although there are some differences in certain sections of the city.
- In 1972, the U.S. Government adopted the one-rat-per-person ratio as the standard for evaluating rat populations in cities and other jurisdictions.
- A rat's litter can include as many as 12 offspring. Rats typically are born 21 to 23 days after the mating took place.