A multislit channel isolator with narrow vertical and wide horizontal fields of view has been used on a high-speed streaking camera to measure two-dimensional return stroke velocities within 1 km of the ground. The slits serve to isolate small vertical sections of the return stroke channel of the order of tens of meters. The isolated sections in the object plane are separated by a vertical distance of the order of a few hundred meters. Data are obtained a writing rate of 8.5¿104 mm s-1 with a time resolution of 2.3 μs. All film was calibrated for the emulsion's nonlinear response to light. Measurements of 12 strokes in three multistroke flashes yield return stroke velocities which range from 2¿107 to 12¿107 m s-1 with an estimated systematic error which varies from 30 to 60%. Velocities in one multistroke flash vary by a factor of 4 between the lowest and highest values. A higher relative intensity was detected in the upper parts of the channel relative to the lower. This may reflect the greater excitation of neutral atomic species in the upper channel and is a characteristic of lightning photographs obtained with red extended photographic emulsions.