Boston is the capital city of Massachusetts and where Ellie was born and subsequently lived before meeting Joel. As of 2033, FEDRA and the military currently control it, the city acting as one of the last functioning Quarantine Zones in America.
After the cordyceps brain infection outbreak around late September 2013, Boston transformed from a heavily populated, bustling city into a military controlled Quarantine Zone. Under martial law, soldiers have set up various checkpoints throughout the city. Military personnel carry scanners to check suspicious citizens for infection, and the military's infection protocol makes soldiers execute any infected individual on the spot. The authorities deal with distributing rations to the populace, as long as the recipient has the appropriate ration cards. Half-ration weeks are declared whenever there are shortages, sometimes for multiple weeks in a row. Able-bodied civilians are conscripted into work details, both inside and outside the walls. Therefore, drafting notices are handed out to individuals every 6 months.
Although Firefly attacks occur frequently, Boston has not devolved into a total war-zone as other cities had. Indeed, Boston currently doesn't experience riots, and the military's hard crack down on the local Fireflies keeps the zone functioning.
Events of Left Behind
Surprisingly, electricity supplies the city though it is unknown how they managed to maintain so much. Riley revealed that the military secretly had lots of power but kept it for their own use or conserved it, much like with rations, proving this by going into the shopping mall and having Ellie flip the circuit breakers back to restore power to the lights in the shops.
Events of The Last of Us
In the events of The Last of Us, Boston has transformed into a heavily controlled military Quarantine Zone. When the infection spread across the country, the U.S. military created this zone to secure themselves from the infected. Joel traveled all the way from Texas to Boston during the twenty years after his daughter died. Ellie was born in the Boston Quarantine zone; after the death of her mother, Anna, she was looked after by Anna's close friend and leader of the Fireflies, Marlene.
By the year 2033, it is one of the last intact Quarantine Zones left in the entire country. While other zones were overrun by infected or abandoned by the military following uprisings by civilians, the Boston zone did not suffer the same fate. This may be due to the extremely tight security measures employed by the military and an abnormally heavy level of fortification even for a Quarantine Zone. These measures include concrete walls that are at least 30 feet high with searchlight-equipped guard towers, a large "No Man's Land" which stretches a considerable distance from the walls that is routinely patrolled by soldiers , a strict 6:00 PM to 6:00 AM curfew (though some residents ignore it), summary execution of anyone infected with CBI and an aggressive and fairly successful crackdown on the Fireflies.
Despite the heavy military presence, a black market has emerged, where one can buy drugs, weapons, and other illegal goods using ration cards and bullets as currency. Tess and Joel ran most of the smuggling into and out of Boston, and gained a formidable reputation among the smugglers and the inhabitants in the Boston QZ for their ruthless attitude towards those that cross them.
There appears to be two main areas within the city. The first is the upper level, particularly "Areas 1, 3, and 4", generally where the checkpoints are located and most of the apartment buildings where people, like Tess and Joel, reside. The ration lines are also located in these areas. At the checkpoints, there are several soldiers on guard, as well as people regularly checking in at them to access other parts of the city or to start and end a day's shift. People that live in these areas seem to avoid the black market and the smuggling trade, either because of the military being so close to them or because they actually don't want to associate with such an unlawful lifestyle. Despite most people here being well behaved, some can be hostile towards others. The Fireflies seem to attack these areas most often, likely because of the high military presence. Underneath some of the buildings there are tunnels, which smugglers use to get outside the wall and cross illegally to another area of the city, even if it is a more dangerous route. 
The other area is the slums, formally called "Area 5",  typically away from military surveillance. It houses a wharf, an old warehouse and the center of the black market community. This freedom enables the citizens to engage in illegal activities, such as drugs, poker and even boxing matches; betting their ration cards as a way to gain more, thus obtain more food and have an easier life in the zone. The lack of military presence also means the residents are more aggressive; many are rude and some even threaten passersby that they don't recognize.  Robert typically hides here, formerly in "Area 2", retreating to the warehouse and wharf when under threat. Although there typically aren't soldiers there, the sound of gunfire prompts them to check the area, such as when Tess and Joel kill several smugglers in the area.
Furthermore, there were areas within and around the zone that had since been abandoned (such as the shopping mall) or overrun with infected (such as downtown Boston). It was in the mall where Ellie and her friend Riley were bitten. Ellie survived and learned of her immunity whereas Riley succumbed to the bite.  Marlene would later ask Joel and Tess to take Ellie outside the QZ and rendezvous with a Firefly group at the Capitol Building, in return for the return of weapons that Robert stole from them and sold to her. 
- The Boston QZ corresponds to the real-life North End neighborhood of Boston, known for being the oldest residential community in the city and a hub for Italian-Americans.
- Ellie (formerly)
- Liz
- Mark
- Various Fireflies (formerly)
- Various smugglers
- Various soldiers
- ↑ See link
- ↑ Note from Mom
- ↑ 3.0 3.1 3.2 3.3 Boston Q.Z. Map
- ↑ 4.0 4.1 4.2 4.3 4.4 The Quarantine Zone
- ↑ One resident talks angrily at Joel though his friend deters him.
- ↑ Tess is offered some by Terrence
- ↑ Joel witnesses two people boxing in a makeshift arena when passing through
- ↑ One was initially aggressive to Joel when he didn't know his face
- ↑ See the DLC
- ↑ The Outskirts