Note 209 — LETTER VI

With his party, De Smet advanced up the Snake or Lewis River to its forks, of which Henry's is the most northern, rising in Henry's Lake (see ante, p. 175, note 45). This arid valley, of which the missionary speaks, has been proved fertile under the influence of irrigation. Several millions of dollars have in recent years been invested in irrigation canals, along the valley of the upper Lewis, through which runs a spur of the Oregon Short Line Railway.—Ed.