Node cooperation is one unique feature distinguishing wireless sensor networks from conventional wireless networks. In this paper, we explore cooperative geographic routing in coalition-aided wireless sensor networks. We first propose a new communication paradigm, i.e., cooperative data transport, where sensor nodes within a coalition cooperatively transmit data via a three-phase procedure. We then treat the routing path selection as a multistage decision problem, where at each stage, the coalition head would choose the next hop destination to minimize the corresponding energy consumption. Next, we investigate the impact of location errors and synchronization errors on the routing performance degradation. Furthermore, we generalize our study to let the nodes with good channel conditions participate in cooperative forwarding, and keep others silent to reduce energy consumption further. Our results demonstrate that the coalition-aided sensor network architecture is most amenable to cooperative sensor networks, simply because it improves energy efficiency and reduces control overhead significantly.