Recovery for the gray wolf in the lower 48 states is largely focused in 3 areas, the western great lakes, the northern rocky mountains (including the pacific northwest), and on the mexican gray wolf in the southwestern states (Guertin, 2016). The recovery for the species has been different in each respective location.
In the Western Great Lakes gray wolves were never completely gone, with a population surviving in Minnesota and Michigan when the ESA was signed into law (Guertin, 2016). Under protections from the ESA this population was able to expand to Wisconsin, including some migrating south from Ontario. Currently this is the largest population of gray wolves in the lower 48 with around 3,500 animals in 2013 (APHIS, 2021).
Gray wolves were completely extinct in the Northern Rocky Mountains at the time the ESA was signed. Efforts to reintroduce the animal to the region were focused in Yellowstone national park in Montana and Wyoming, along with some in Idaho. This reintroduction was largely successful, with there now being over 1,700 wolves in Montana, Wyoming, and Idaho as of 2015 (Guertin, 2016). These wolves have also migrated westward, starting populations in eastern Oregon and Washington.
The Mexican gray wolf was almost extinct when it was listed. Recovery focused mainly on captive breeding projects. There are 50 captive breeding facilities between the US and Mexico, and experimental populations were set up in New Mexico and Arizona during 1998 called the Mexican Wolf Experimental Population Area. In 2015 this area was expanded to 98.5 million acres of land across the two states (Guertin, 2016). This population of wolves is currently around 100 wolves.