We report a measurement of the energy spectrum of cosmic rays above 2.5×1018 eV based on 215 030 events. New results are presented: at about 1.3×1019 eV, the spectral index changes from 2.51±0.03(stat)±0.05(syst) to 3.05±0.05(stat)±0.10(syst), evolving to 5.1±0.3(stat)±0.1(syst) beyond 5×1019 eV, while no significant dependence of spectral features on the declination is seen in the accessible range. These features of the spectrum can be reproduced in models with energy-dependent mass composition. The energy density in cosmic rays above 5×1018 eV is [5.66±0.03(stat)±1.40(syst)]×1053 erg Mpc−3.Received 20 May 2020Accepted 31 July 2020DOI:https://doi.org/10.1103/PhysRevLett.125.121106Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Research AreasCosmic ray & astroparticle detectorsCosmic ray accelerationCosmic ray composition & spectraCosmic ray propagationCosmic ray sourcesGravitation, Cosmology & Astrophysics