when was it established?
1 September 1967
New York State Department of Transportation

The first head of the New York State Department of Transportation (effective from 1 September 1967) was the former head of the New York State Department of Public Works John Burch McMorran (1899–1991). 
which places are connected by new york state route 146? Gallupville, Mechanicville and Schenectady. which counties does it pass through? Schoharie County. when was it designated as route 146? 1930 was it known by any other name earlier? UNANSWERABLE which authority is in charge of maintaining it? The New York State Department of Transportation.
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New York State Department of Transportation [SEP] History
The history of the New York State Department of Transportation and its predecessors spans over two centuries: The first head of the New York State Department of Transportation (effective from 1 September 1967) was the former head of the New York State Department of Public Works John Burch McMorran (1899–1991). The first Executive Deputy Commissioner of the New York State Department of Transportation was Edward Burton Hughes, who had formerly been Deputy Superintendent of the New York State Department of Public Works, a role he had worked in continuously since 1952. Both appointments were engaged by Governor Nelson Rockefeller.