=National Aspects of Slavery.=--It may be asked why it was that slavery, founded originally on state law and subject to state government, was drawn into the current of national affairs. The answer is simple. There were, in the first place, constitutional reasons. The Congress of the United States had to make all needful rules for the government of the territories, the District of Columbia, the forts and other property under national authority; so it was compelled to determine whether slavery should exist in the places subject to its jurisdiction. Upon Congress was also conferred the power of admitting new states; whenever a territory asked for admission, the issue could be raised as to whether slavery should be sanctioned or excluded. Under the Constitution, provision was made for the return of runaway slaves; Congress had the power to enforce this clause by appropriate legislation. Since the control of the post office was vested in the federal government, it had to face the problem raised by the transmission of abolition literature through the mails. Finally citizens had the right of petition; it inheres in all free government and it is expressly guaranteed by the first amendment to the Constitution. It was therefore legal for abolitionists to present to Congress their petitions, even if they asked for something which it had no right to grant. It was thus impossible, constitutionally, to draw a cordon around the slavery issue and confine the discussion of it to state politics. There were, in the second place, economic reasons why slavery was inevitably drawn into the national sphere. It was the basis of the planting system which had direct commercial relations with the North and European countries; it was affected by federal laws respecting tariffs, bounties, ship subsidies, banking, and kindred matters. The planters of the South, almost without exception, looked upon the protective tariff as a tribute laid upon them for the benefit of Northern industries. As heavy borrowers of money in the North, they were generally in favor of "easy money," if not paper currency, as an aid in the repayment of their debts. This threw most of them into opposition to the Whig program for a United States Bank. All financial aids to American shipping they stoutly resisted, preferring to rely upon the cheaper service rendered by English shippers. Internal improvements, those substantial ties that were binding the West to the East and turning the traffic from New Orleans to Philadelphia and New York, they viewed with alarm. Free homesteads from the public lands, which tended to overbalance the South by building free states, became to them a measure dangerous to their interests. Thus national economic policies, which could not by any twist or turn be confined to state control, drew the slave system and its defenders into the political conflict that centered at Washington.