In this paper, we study cooperative broadcast using multiple levels of relays for high-density 1-D networks and compare its behavior with noncooperative multihop broadcast. The advantage of cooperative broadcast over multihop transmission has been well studied for both high-density and extended 2-D networks. We analyze high-density 1-D networks, and approximate them as a continuum of nodes. Our analysis shows that the broadcast behavior depends on three different regimes of the pathloss exponent and the type of transmission (being bidirectional or unidirectional). We present analytical expressions for successful broadcasting as a function of source and relay powers, decoding threshold and the noise power. We also compare cooperative and noncooperative broadcast in terms of power efficiency and show that cooperative broadcast is substantially more efficient under bidirectional transmission; however it is power inefficient if the transmission is unidirectional.