Although largely considered a problem of developing countries today, trachoma was once extremely common in parts of the United States and accounted for a large proportion of blindness. Under an act signed by President Woodrow Wilson in June 1913, a substantial part of the U.S. Public Health Service budget was earmarked to fight trachoma. Numerous trachoma surveys revealed the presence of a "trachoma belt" across the mid United States, and the prevalence of trachoma reached as high as 50-90% among school children on some Indian reservations. Crowding, poverty, and lack of clean water and hygiene were identified as risk factors for trachoma. Measures taken to combat trachoma included isolation schools for infected children, special government trachoma hospitals and field clinics, screening of immigrants to the U.S., improvements in hygiene and sanitation, and antibiotic therapy. The Indian Health Service utilized radical eyelid surgery with reportedly disastrous consequences. Prevalence surveys show a clear decline in trachoma in the U.S. during the twentieth century.