The ABA has recent released its statistics for the Class of 2018, or matriculation and law school enrollment for 2015. First-year matriculants totaled 37,058 at 204 ABA-accredited law schools. That's down from 52,488 in 2010. And that's the lowest number since 1973, when 37,018 matriculated to 151 law schools.
Additionally, total law school enrollment declined from 119,775 to 113,900, as smaller and smaller 1L classes enter and the larger classes graduate. That's the smallest number since 1977, which had a total JD enrollment of 113,080 among 163 ABA-accredited law schools.
(As a brief note about the visualizations, I chose not to begin the Y-axis at 0 in order to represent the relative changes over the class sizes.)