ARC has been serving the co-op community in Riverdale and throughout NewYork City for more than 35 years the Association of Riverdale Cooperatives and Condominiums, Inc. (ARC) is a domestic non-profit corporation, certified under section 402 of the Not-for-Profit Corporation Law. It was formed for the mutual advancement of the interests of its members engaged in the ownership and operation of buildings owned cooperatively or in condominium.