By measuring the frequency drift rate of type III bursts observed continously from 13.8 MHz to a few kHz, we have derived the electron density distribution in the ecliptic plane, from the corona to 1 AU. This method is a powerful probe to explore the region between1.8&hthinsp;Roto 1 AU, most of which is not observed by coronographs. The observations were made by the radio experiment WAVES aboard the spacecraft Wind. We have selected type III bursts whose trajectories intersect the spacecraft, as determined by the presence of burst-associated Langmuir waves, or by energetic electrons observed by the 3-D Plasma experiment. For these bursts we are able to determine the mode of emission, the electron density at 1 AU, the distance of emission regions along the spiral, and the time spent by the beams as they proceed from the low corona to 1 AU. An average density model is derived, valid for solar minimum:ne=3.3×105r−2+4.1×106r−4+8.0×107r−6&hthinsp;cm−3,withrin units ofRo.We show how, for a given day, the density distribution departs from the average model. As an application, we derive the speed of the shock of 7 April 1997 which produced a type II burst from 75 to 0.9 MHz (1.2 to13&hthinsp;Ro). For this event, a flare, a fast CME and the initiation of the type II burst occurred simultaneously to with in a few minutes. The derived speed of the type II shock in the solar wind leads to the arrival of the interplanetary shock at the Earth on 10 April at 1300 UT, as was observed. ©1999 American Institute of Physics.