SR 231 begins at Jct SR 23 a short distance north of I-90/US 395 exit 245 near Sprague. From SR 23, SR 231 heads north via Edwall to Jct US 2 about 3 miles west of Reardan, SR 231 joins US 2 and heads east to Reardan. At Reardan, SR 231 leaves US 2 and heads north, crossing the Spokane River a short distance downstream from Long Lake Dam. From the Spokane River, SR 231 continues north via Ford, Springdale, and Valley, ending at Jct US 395 about 6 miles south of Chewelah. SR 231 is 74.97 miles long.
Before 1964, SR 231 from Sprague to Reardan had been SSH 2G and from Reardan to US 395, SSH 3J.
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