Apportionment

apportion v. to distribute proportionately

In the context of the Constitution, apportionment means that each state gets a number appropriate to its population. For example, Representatives are apportioned among the states, with the most populous getting the greater share.Direct taxes (of which there are none today) were to be charged to the states in this manner as well.

The need for apportionment of taxes, and the reason for it, is difficult for us to imagine today, but there were good reasons for it. The following is an explanation of the need for the Direct Tax Apportionment clause. It was written by Supreme Court Justice Paterson in Hylton v US (3 US 171 [1796]):

The constitution declares, that a capitation tax is a direct tax; and both in theory and practice, a tax on land is deemed to be a direct tax... The provision was made in favor of the southern states; they possessed a large number of slaves; they had extensive tracts of territory, thinly settled, and not very productive. A majority of the states had but few slaves, and severa lof them a limited territory, well settled, and in a high state of cultivation.The southern states, if no provision had been introduced in the constitution,would have been wholly at the mercy of the other states. Congress in such case,might tax slaves, at discretion or arbitrarily, and land in every part of the Union, after the same rate or measure: so much a head, in the first instance,and so much an acre, in the second. To guard them against imposition, in these particulars, was the reason of introducing the clause in the constitution.