Since the mid-20th century, the standard U.S. high school and college math curriculum has been based on two years of algebra and a year of geometry, preparing students to take classes in pre-calculus followed by calculus. Students' math pursuits have been differentiated primarily by how far or how rapidly they proceed along a clearly defined trajectory that has changed little since then. Evolutions in various disciplines and in learning sciences are calling into question the relevance and utility of this trajectory as a requirement for all students. The emerging movement is toward differentiated "math pathways" with distinct trajectories tied to students' goals. Alternatives emphasizing statistics, modeling, computer science, and quantitative reasoning that are cropping up in high schools and colleges are beginning to challenge the dominance of the familiar math sequence. The drive toward acknowledging the importance of multiple domains within math is prompted largely by two developments: (1) technological tectonics; and (2) demand for deeper learning. Decisions about math requirements and expectations will have a major impact on the academic opportunities of millions of students nationally. This is the first report in "Degrees of Freedom," a series that explores the role of math as a gatekeeper in higher education. This report examines the move toward differentiated math pathways linked to students' academic majors, highlights some obstacles to implementing them, and discusses some principles for addressing those obstacles. [For part 2 of this series, see ED564295. For part 3 of this series, see ED564294.]