Archaeology has long been an accepted tool for studying prehistoric cultures. Relatively recently the same techniques have been systematically applied to studies of the more immediate past. This has been called "historical archaeology," a term that is used in the United States to refer to any archaeological investigation into North American sites that postdate the arrival of Europeans.
Back in the 1930's and 1940's, when building restoration was popular, historical archaeology was primarily a tool of architectural reconstruction. The role of archaeologists was to find the foundations of historic buildings and then take a back seat to architects.
The mania for reconstruction had largely subsided by the 1950's and 1960's. Most people entering historical archaeology during this period came out of university anthropology departments, where they had studied prehistoric cultures. They were, by training, social scientists, not historians, and their work tended to reflect this bias. The questions they framed and the techniques
They used were designed to help them understand, as scientists, how people behaved. But because they were treading on historical ground for which there was often extensive written documentation, and because their own knowledge of these periods was usually limited, their contributions to American history remained circumscribed. Their reports, highly technical and sometimes poorly written, went unread.
More recently, professional archaeologists have taken over. These researchers have sought to demonstrate that their work can be a valuable tool not only of science but also of history, providing fresh insights into the daily lives of ordinary people whose existences might not otherwise be so well documented. This newer emphasis on archaeology as social history has shown great promise, and indeed work done in this area has lead to a reinterpretation of the United States past.
In Kingston, New York, for example, evidence has been uncovered that indicates that English goods were being smuggled into that city at a time when the Dutch supposedly controlled trading in the area. And in Sacramento an excavation at the site of a fashionable nineteenth-century hotel revealed that garbage had been stashed in the building's basement despite sanitation laws to the contrary.
What does the passage mainly discuss？

A. Why historical archaeology was first developed.
B. How the methods and purpose of historical archaeology have changed.
C. The contributions architects make to historical archaeology.
D. The attitude of professional archaeologists toward historical archaeology.