In 1851, following a decline in business after the Great Famine, Tinsley and his wife Lucy and their nine children emigrated to the US. They sailed from Waterford to New York via Liverpool before settling in Cincinnati. His first major commission in his adopted country was the original North Western Christian University building which he began in the Winter of 1852-53. He completed several other commissions, among them Christ Church Cathedral on Monument Circle in Indianapolis, River View Cemetery in Aurora, Indiana, work for Rockwell, Kenyon (Ascension Hall), and Wabash colleges, as well as Ohio Wesleyan University, and Bascom Hall at the University of Wisconsin. It is likely that he designed Christ Church at the Quarry (1863) in Gambier, Ohio, near Kenyon College. He was also the architect for Grace Episcopal Church in Pomeroy, Ohio, and St. Philip's Episcopal Church, Circleville, Ohio in 1866-1867. His last major work was the Ohio State School for the Blind at Columbus, Ohio. Following his death in 1885, he was interred at Crown Hill Cemetery in Indianapolis.