This paper presents a state-of-the-art review of recent developments in three-dimensional (3D) analysis for transportation planning and highway design. As background, the concept of dimension is briefly discussed and examples of transportation-related disciplines are given in zero, one, two, three, and four dimensions. Two types of 3D models are described: visualization models and analytical models. Transportation planning applications include system planning (e.g., data collection modeling), corridor/project planning (e.g., traffic calming), and environmental analysis (e.g., air quality assessment). Highway design applications include route planning (e.g., preliminary route selection), geometric design (e.g., combined alignment), and structural design (e.g., pavement design). This paper is sponsored by the ASCE Urban Transportation Division’s Planning Committee and the Highway Division’s Geometric Design and Operations Committee. By summarizing current and emerging developments of 3D analysis in transportation, the committees hope to raise awareness of this powerful tool and to help stimulate its applications in other transportation areas.