Over the past decade, computers have been increasingly utilized in transmission line corridor and route planning, offering substantial benefits in terms of accuracy, speed, cost-efficiency, and the ability to manage and present large volumes of spatial data. This study provides a comprehensive review of computer-assisted transmission line planning, with a focus on practices in North America. It introduces fundamental concepts and broader considerations relevant to the selection, adaptation, or development of such systems. The report profiles ten representative planning systems, detailing the involved agencies, project examples, methodologies, software and hardware used, and key contacts. A detailed case study illustrates the planning method of one comprehensive system. Additionally, ten other organizations engaged in relevant research or applications are briefly discussed. The study highlights the diverse ways in which computers are applied, ranging from integration with broader facility planning—including power stations and infrastructure—to focused applications like satellite-based land use analysis and visual simulation. It offers a valuable reference for future development and application of computer-assisted systems in transmission line planning.