Here's why:

* Diet: They are omnivores, eating a wide variety of food sources, including decaying organic matter, food scraps, paper, and even other insects.

* Habitat: They can thrive in a wide range of environments, from warm, humid locations like kitchens and bathrooms to cooler, drier places like basements and sewers.

* Tolerance: They are incredibly resilient and can tolerate a wide range of temperatures and humidity levels.

This adaptability allows American cockroaches to exist in a variety of environments and feed on a wide range of resources, making them a highly successful and widespread species.