The exceptionally strong and long-lived Arctic stratospheric polar vortex in 2019/2020 resulted in large transport anomalies throughout the fall-winter-spring period from vortex development to breakup. These anomalies are studied using Aura MLS long-lived trace gas data for N₂O, H₂O,and CO, ACE-FTS CH₄ , and meteorological and trace gas fields from reanalyses. Strongest anomalies are seen throughout the winter in the lower through middle stratosphere (from about 500K through 700K), with record low (high) departures from climatology in N₂O and CH₄ (H₂O). CO also shows extreme high anomalies in midwinter through spring down to about 550K. Examination of descent rates, vortex confinement, and trace gas distributions in the preceding months indicates that the early-winter anomalies in N₂O and H₂O arose primarily from entrainment of air with already-anomalous values (which likely resulted from transport linked to an early January sudden stratospheric warming the previous winter during a favorable quasi-biennial oscillation phase) into the vortex as it developed in fall 2019 followed by descent of those anomalies to lower levels within the vortex. Trace gas anomalies in midwinter through the late vortex breakup in spring 2020 arose primarily from inhibition of mixing between vortex and extravortex air because of the exceptionally strong and persistent vortex. Persistent strong N₂O and H₂O gradients across the vortex edge demonstrate that air within the vortex and its remnants remained very strongly confined through late April (mid-May) in the middle (lower) stratosphere.