The number of home sales in the first quarter dropped in Westchester and Rockland for the first time in four years, amid the continuing erosion of entry-to-mid-level-home inventory, according to housing market reports issued by two real estate organizations.

The lack of inventory has been an issue, but the implications of the new tax laws might have been an additional hindrance to home sales in the first quarter, said Barry Kramer, president of the Hudson Gateway Association of Realtors (HGAR) and principal broker for Westchester Choice Realty.