Timing of State and Territorial COVID-19 Stay-at-Home Orders and Changes in Population Movement - United States, March 1-May 31, 2020 - Moreland, A; Herlihy, C; Tynan, M A; CDC Public Health Law Program; CDC COVID-19 Response Team, Mitigation Policy Analysis Unit (MMWR Morb Mortal Wkly Rep, 2020)