Background: Physical activity (PA) is associated with health and academic benefits among children, but many schools do not meet national recommendations. This study examined school-based PA practices in nationally representative samples of public elementary schools, and geographic variations in those practices. Methods: Mail-back surveys were used to gather data from 578 public elementary schools during the 2006-2007 school year and 680 public elementary schools during the 2009-2010 school year. Results: Nationwide, only 1 in 5 schools met the national recommendation of at least 150 minutes of physical education (PE) per week, although PE was more prevalent in the South. Nearly three-fourths of schools nationwide met recommendations for 20 or more minutes of recess daily, and this was more prevalent in the Midwest but less so in the South. Approximately 40% of schools offered sports and approximately 40% offered other opportunities for PA during the school day. The only practice that increased over time was formal classroom instruction on PA. Conclusions: There has been little change in elementary school-based PA practices nationwide in recent years. With the upcoming renewal of the Elementary and Secondary Education Act, policymakers have an important opportunity to promote increased PA in schools. (Contains 1 table.)