locomotives and cars, until railway engineers learned by experience the
wisdom of stopping their trains whenever there were buffaloes crossing
the track. On this feature of the buffalo's life history a few detailed
observations may be of value.

Near the mouth of the White River, in southwestern Dakota, Lewis and
Clark saw (in 1806) a herd of buffalo which caused them to make the
following record in their journal:

"These last animals [buffaloes] are now so numerous that from an
eminence we discovered more than we had ever seen before at one time;
and if it be not impossible to calculate the moving multitude, which
darkened the whole plains, we are convinced that twenty thousand would
be no exaggerated number."

When near the mouth of the Yellowstone, on their way down the Missouri,
a previous record had been made of a meeting with other herds:

"The buffalo now appear in vast numbers. A herd happened to be on their
way across the river [the Missouri]. Such was the multitude of these
animals that although the river, including an island over which they
passed, was a mile in length, the herd stretched as thick as they could
swim completely from one side to the other, and the party was obliged to
stop for an hour. They consoled themselves for the delay by killing four
of the herd, and then proceeded till at the distance of 45 miles they
halted on an island, below which two other herds of buffalo, as numerous
as the first, soon after crossed the river."[22]

[Note 22: Lewis and Clark's Exped., II, p. 395.]