Final answer:
The specific Boston hotel that first installed indoor plumbing is not mentioned in the references, but the overall progress in sanitation during the late nineteenth and early twentieth centuries, which included the spread of indoor plumbing, significantly improved the standard of living.
Step-by-step explanation:
The hotel in Boston that became the first in the U.S. to install indoor plumbing is not directly mentioned in the provided reference information. However, it can be noted that the changes in sanitation improved the cleanliness, comfort, and health of people of all classes during the late nineteenth and early twentieth centuries. Indoor plumbing became part of a new cult of cleanliness among the middle class, and innovations like mass-produced bathroom fixtures and the development of flush toilets allowed hotels and homes to become more sanitary and comfortable. While the text does not name a specific hotel in Boston, the general technological advancements in the city surrounding the textile industry, as led by the Boston Manufacturing Company, can indirectly attest to the improvements in living standards that would also have affected accommodation services like hotels.