What historical pressure seemed less severe or was managed differently in the West compared to the Eastern US, affecting *I. pacificus* distribution?
Deforestation and intense hunting pressure severely reducing deer populations.
The stability of the *I. pacificus* range in the West, in contrast to the expansion observed in *I. scapularis* in the East, is tied to differing historical pressures on host populations. In the Eastern US during the late 1800s and early 1900s, significant deforestation combined with intense hunting dramatically reduced deer populations. This likely forced the eastern tick into small, isolated refugia. Conversely, in the West, the combined pressures of deforestation and deer depredation were apparently less severe or subject to different management strategies. This difference allowed deer populations, the main reproductive host for *I. pacificus*, to remain numerous and widely distributed, thereby stabilizing the tick's own range.
