Wireless sensor networks (WSNs) have been extensively researched recently. This paper makes two contributions to this field. First, we promote a new concept of long-thin (LT) topology for WSNs, where a network may have a number of linear paths of nodes as backbones connecting to each other. These backbones are to extend the network to the intended coverage areas. At the first glance, a LT WSN only seems to be a special case of numerous WSN topologies. However, we observe, from real deployment experiments, that such a topology is quite general in many applications and deployments. The second contribution is that we show that the address assignment and thus the tree routing scheme defined in the original ZigBee specification may work poorly, if not fail, in a LT topology. We thus propose simple, yet efficient, address assignment and routing schemes for a LT WSN. Simulation results and prototyping experiences are also reported.