Abstract: The present invention is directed to a block system including first and second blocks. Each block has an outer surface with a pair of locking channels formed within the outer surface. The locking channels are spaced apart from each other. Each locking channel has a narrower outer slot portion extending through the outer surface and a wider inner slot portion extending from the outer slot portion into its respective block. A first pair of locking members are provided for coupling the blocks together by insertion into the locking channels of the blocks with the locking channels of the first block being positioned to join with the locking channels of the second block. The locking members have a cross-section with wider outer edges dimensioned to fit in the inner slot portions and a narrower mid-section dimensioned to fit in the outer slot portions.