The Jackson County Hydro Dam Reservoir is the hydroelectric plant that powers Tommy's town of Jackson, and where Joel and Ellie finally find Tommy in Tommy's Dam. It is the setting of the Hydroelectric Dam section and a bandit attack.
Maria and her riflemen hold you at gunpoint at the gate until Tommy recognizes Joel. Tommy and his crew are repairing a broken turbine, and the pair give you a tour. Joel asks Tommy privately to take Ellie to the Fireflies, and Tommy refuses before bandits storm the plant.
With the plant held, Tommy talks Maria into letting him take Ellie. Ellie, angry that Joel kept her out of the decision, rides off, and Joel and Tommy follow her toward Hidden Pines Corral.
Hidden Pines Corral
Hidden Pines Corral is the abandoned ranch house in the Jackson County woods where Joel and Tommy catch up with Ellie after she rides away from the dam. It is the setting of the Ranch House section of Tommy's Dam, ending in a bandit ambush.
Austin
Austin, Texas is where The Last of Us Part I begins: the Prologue of Hometown plays out on outbreak night in September 2013 as Joel, his daughter Sarah and his brother Tommy try to escape the city. It is the only region you visit before the 20-year time skip.
Boston
Boston, Massachusetts is the first region after the time skip and the city where Ellie grew up. You play The Quarantine Zone and The Outskirts here, and Left Behind's flashbacks with Riley take place in the same city. FEDRA holds the North End as one of the last working quarantine zones in the country.
Lincoln
Lincoln is a small Massachusetts town a few miles from Boston and the setting of Bill's Town, the fourth chapter. Joel and Ellie come here to call in a favor from Bill, a paranoid survivor who has rigged the whole town with traps, because they need a working vehicle.