Illinois Electric Load Zones & the Distribution Cooperatives

IPA “Load Zone 4” = MISO Local Resource Zone 4 = the Ameren Illinois footprint

Click any county or co-op marker for details. Zone shading follows utility service territory (approx.; territories can split counties). Sources: ICC “Resource Adequacy in MISO Zone 4” 12/17/2018 · AIEC (aiec.coop) · SWECI (sweci.com). Prepared 2026-07-15.

Layers & Legend

MISO Zone 4 (Ameren)

PJM / ComEd (north)

MISO Zone 1 (Dairyland NW)

Co-op HQ markers

Southwestern Electric (Greenville)

G&T co-ops (PPI, SIPC)

County boundaries

22 of 25 AIEC distribution co-ops sit inside MISO Zone 4. The only 2 exceptions are Jo-Carroll Energy & Rock Energy (far-NW, Dairyland / MISO Zone 1).