Final answer:
The Red Line segment from Harvard to Charles/MGH does not have a specific construction date in the provided material, but Boston's subway system began with the Tremont Street Subway in 1897, marking the transition from trolleys to subways.
Step-by-step explanation:
The Red Line subway from Harvard to Charles/MGH in Boston is part of a larger transit system that has evolved over time. While the referenced material does not provide the specific date for the construction of this segment, Boston's subway system began with the opening of the Tremont Street Subway, the oldest subway tunnel in the United States, which opened on September 1, 1897. This marked the transition from trolleys to subways in Boston, helping alleviate congested streets, as previously trolleys and other modes of transportation such as horse-drawn carriages led to frequent accidents.
The subsequent expansion of subway lines, including the Red Line, was part of the broader development of transit systems that revolutionized travel, making it possible to cover distances in significantly less time compared to earlier modes of transportation. However, for precise dates on when the Red Line segment between Harvard and Charles/MGH was constructed, additional detailed research into Boston's urban transit history would be required.