Slingerland & Clark, P.C. Attorneys Slingerland & Clark, P.C. Visit Website 499 East State Street Sycamore, IL 60178 (815) 895-5141 (815) 895-8567 (fax) Facebook About About Slingerland & Clark, P.C. is a locally owned, boutique law firm, founded in 2004. We have over 60 years of combined experience in handling a wide variety of civil and criminal legal matters.