CHICAGO (S&P Global Ratings) May 8, 2017--S&P Global Ratings raised its long-term rating to'A'from'A-'on Will County School District No. 81 (Union) , Ill.'s general obligation (GO) bonds. The outlook is stable."The raised rating reflects our view of the district's recent operational surpluses and improvement in its general fund reserve levels,"said S&P Global Ratings credit analyst David Smith."The ratings further reflect our view of the district's extremely strong market value per capita and rapid amortization,"Mr. Smith added. Will County School District No. 81 (Union) serves an estimated population of 1,431. The grade K-8 district serves residents on the southeast side of Joliet and in a small portion of New Lenox, about 42 miles