To study the benefit of soil stabilization, four test pavement sections were constructed on State Route 2 in Erie County, Ohio in 2001, with subgrade stabilized with 6% cement, 5% lime, 3% lime plus 3% cement, for three stabilized sections, and one control section without stabilization. To quantify the structural strength gain of the stabilized subgrade, the Falling Weight Deflectometer (FWD) testing was conducted yearly after the construction of these test sections. The back-calculation technique is then used to estimate the modulus of the stabilized soils. The preliminary results based on the testing results of first three years show that the soil stabilized with 6% cement gains most strength initially, followed by the 3% lime plus 3% cement. However, interestingly, the 5% lime stabilized subgrade continues to gain strength three years after construction. This paper will examine the strength of stabilized subgrade of test sections with more years of FWD testing data after construction. The analysis is expected to provide valuable information on the long-term performance of soil stabilization used with pavements constructed in a cold region.