until both the sciences of geology and engineering hydrology were far enough advanced to be of practical help, in the late 1800s, hydrogeologic progress was stymied. with the opening of the west in the late 1180s, hydrogeologic progress was stymied. with the opening of the west in the late 1860s the demand came. hydrogeologists were needed to find irrigation water for the arrid lands. concomitantly, in the south, ground water was needed for the arid growing rice, corn, and cotton. the rapid growth of cities, especially in the north, required hydrogeologists to find safe supplies of clean, pure water to replace polluted surface-water sources. by the early 1900s engineering techniques and equipment needed to drill and pump the deep wells and to evaluate the aquifer pumping tests were available, satisfactory for the times, but clumsy and awkward by modern standards. by 1912, the beginning of the 'meinzer era', the u. s geological survey had developed into te foremost governmental scientific organization in the world and its small car cadre of hydrogeologists were world leaders in their science. (edited author abstract) 92 refs