The letter, which was from Deputy Commissioner of Historic Preservation Ruth Pierpont, was addressed to Lewisboro Supervisor Peter Parsons.
Pierpont wrote that the historic district was listed on the national register on July 28.
"Listing on the National Register recognizes the importance of these properties to the history of our country and provides them with a measure of protection," Pierpont wrote.
The deputy commissioner added that federal and state tax benefits are available for affected property owners.
Parsons announced the news at Monday's town board meeting.
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