The native range of this commonly planted species (pecan) was originally centered in the lower Mississippi Valley, but even before Virginian settlement it is likely that people extended its distribution. In Ky. native trees appear to have been locally frequent near the Ohio Rv. upstream to at least JEFF, and a few colls. suggest native status as far as TRIM (DHL) and KENT (B). C. illinoinensis also extended up the Cumberland Rv. to the Nashville Basin (Ch), but its status further upstream in Ky. remains uncertain. Included here as open dots are the unverified historical data of Gm. Excluded are colls. that probably came from planted or escaped trees; see also CW. Various cultivars or selections are often planted or grafted. There are also rare natural or artificial hybrids with laciniosa, ovata and other species. Note that the old spelling "illinoensis" (F) was incorrect (Cr, FNA 3). The state champion is in FULT (KDF 2020): 175 m dbh, 32 m tall, 34 m wide.