ASK TOM: Illinois average rainfall vs dries and wettest states

Dear Tom,
The flooding across Illinois this spring makes me wonder what the state’s average rainfall is and how that amount compares with the wettest and driest states and the national average.
— Ken Overland
Dear Ken,
Nationwide (excluding Alaska and Hawaii), average annual precipitation is 30.5 inches. It’s not distributed evenly, of course. Areas to the east of the Mississippi River are wetter, as is the Pacific Northwest.
A swath of the nation from about Iowa to eastern Texas is near the national average. The Southwest, intermountain West and high Great Plains are drier.
On average, though, Louisiana, with 55 inches, is our wettest state; Nevada, with a scant 9 inches annually, is the driest. Illinois, with 37 inches, ranks 27th — 26 states wetter, 21 drier.