Does anyone know where to find a growth chart for children in the u.S.?

CDC. This website should be helpful: http://www.Cdc.Gov/growthcharts/clinical_charts.Htm.
Growth chart. The national center for health statistics has charts. So does the american academy of pediatrics(aap. Org). You can try free sites like the human growth foundation, or the magic foundation on growth.
Your pediatrician. Most pediatrician have growth charts for infants and children and for boys(blue)and girls(pink) and at each well visit they chart wight and height and percentile graph is charted talk to your child pediatrician or any pediatric clinic.