From kindergarten through high school, the mathematics education in public schools in the United States has historically varied widely from state to state, and often even varies considerably within individual states. With the recent adoption of the Common Core Standards by 45 states, mathematics content across the country is moving into closer agreement for each grade level.
Each state sets its own curricular standards and details are usually set by each local school district. Although there are no federal standards, 45 states have agreed to base their curricula on the Common Core State Standards in mathematics beginning in 2015. The National Council of Teachers of Mathematics (NCTM) published educational recommendations in mathematics education in 1991 and 2000 which have been highly influential, describing mathematical knowledge, skills and pedagogical emphases from kindergarten through high school. The 2006 NCTM Curriculum Focal Points have also been influential for its recommendations of the most important mathematical topics for each grade level through grade 8.
The United States differs from most other countries in that mathematics is generally separated by topic at the high-school level. Two years are devoted entirely to algebra and one year entirely to geometry. (A few localities follow an integrated curriculum, as in other countries.) The algebra-geometry-algebra sequence is followed by a course often called pre-calculus for college-bound students. Pre-calculus usually combines advanced algebra (or "Algebra 3") and geometry with trigonometry and other topics in preparation for a course in calculus, which is taken in the 12th grade at high school or the first year of university studies. The age at which the algebra-geometry-algebra sequence begins varies according to locality and student ability. Other optional mathematics courses may be offered, such as statistics or business math.