e plains with the men of the gulf plains. The inevitable
interpenetration of Northern and Southern interests in Illinois,
resulting from these contacts, is the most important fact in the
social and political history of the State. It bred in Illinois
statesmen a disposition to compromise for the sake of political
harmony and economic progress, a passionate attachment to the Union as
the _sine qua non_ of State unity, and a glowing nationalism. Illinois
was in short a microcosm: the larger problems of the nation existed
there in miniature.

When Illinois was admitted to the Union in 1818, all the organized
counties lay to the south of the projected national road between Terre
Haute and Alton, hence well within the sphere of surrounding Southern
influences. The society of Illinois was at this time predominantly
Southern in its origin and characteristics.[303] Social life and
political thought were shaped by Southern life and Southern thought.
Whatever points of contact there were with the outside world were with
the Southern world. The movement to make Illinois a slave State was
motived by the desire to accelerate immigration from the South.

But people had already begun to come into the State who were not of
Southern origin, and who succeeded in deflecting the current of
Illinois politics at this critical juncture. The fertile river bottoms
and intervening prairies of southern Illinois no longer sufficed. The
new comers were impelled toward the great, undulating prairies which
expand above the 39th parallel. The rise of new counties marks the
volume of this immigration;[304] the attitude of the older settlers
toward it, fixes sufficiently its general social character. This was
the beginning of the "Yankee" invasion, New York and Pennsylvania
furnishing the vanguard.

As the northern prairies became accessible by the lake route and the
stage roads, New England and New York poured a steady stream of
homeseekers into the Commonwealth. By the middle of the century, this
Northern immigration had begun to inundate the northern counties and
to overflow into the interior, where it met and mingled with the
counter-current. These Yankee settlers were viewed with hostility, not
unmixed with contempt, by those whose culture and standards of taste
had been formed south of Mason and Dixon's line.[305]

This sectional antagonism was strengthened by the rapid commercial
advance of northern Illinois. Yankee enterprise and thrift worke