All freeways usually replace another older route. I-15 replaced U.S. 91, I-5 replaced U.S. 99, and I-90 replaced U.S. 10. Before Interstate 90 was built in the 60's and 70's, U.S. Highway 2 until 1939, and U.S. Highway 10 and 395 went thru Fishtrap, Tyler, Cheney, and Sprague. Washington State Highway 904 quickly was built over the old road between Tyler and Cheney, making the route straighter and wider. Sprague HWY Road was built almost over the old highway between Fishtrap and Sprague. The highway between Tyler and Sprauge was paved over and re-graded for constructing I-90. When I originally placed the cache, I was under the impression that this was the old route based on the road name. Still, I have discovered since that many roads that were built after the construction of a new highway take on similar names (Vintage US 95 in North Idaho is a new example, as the previous routing is under the new highway). Hope this clears up any .