Since the development of the directional Doppler by McLeod in 1967, methods of acquiring, analyzing, and displaying blood velocity information have been under constant exploration. These efforts are motivated by a variety of interest and objectives including, to: a) simplify clinical examination, examiner training, and study interpretation, b) provide more hemodynamic information, and c) reduce examination variability and improve accuracy. The vector Doppler technique has been proposed as one potential avenue to achieve these objects. Vector Doppler systems are those that determine the true 2D or 3D blood flow velocity by combining multiple independent velocity component measurements. Most instruments can be divided into two broad categories: 1) cross-beam and 2) time-domain. This paper provides a brief synopsis of the progression of vector Doppler techniques, from its onset in 1970 to present, as well as possible avenues for future work. This is not intended to be a comprehensive review of all vector Doppler systems.