Rolling prairies, continental climate (cold winters, warm summers), buffalo/grama/needlegrass, bison, pronghorn, meadowlarks.
Similar terrain; slightly warmer winters, hotter summers; switchgrass appears; similar wildlife.
Subtropical climate (mild winters, very hot summers); bluestem grass; similar fauna.
Mountains and deserts; arid; sagebrush, bunchgrass, cactus, juniper, pine; pronghorn, deer, elk, mountain lions; hawks, eagles, owls.
Each subregion's climate and vegetation create distinct ecological zones.