Time-calibrated phylogeny of severe acute respiratory syndrome coronavirus 2 variant B.1.1.7, New York and other states, USA, December 2020–April 2021. Left panel represents a maximum-likelihood phylogeny of 1,195 genomes from New York and other states generated in IQTree 1.6.12 (20) with timescale inferred by TreeTime 0.7.6 (22) and ancestral state reconstruction performed in BEAST 2.6.2 (23). The tree was rooted with a P.1 genome (not shown). Faceted panels indicate the source of B.1.1.7 introductions into different regions of New York and other states (domestic). Only introductions supported by an ancestral state probability of >0.7 are shown. Bottom panel shows locations sampled and sample sizes. A, April; J, January; O, October.