ing cargoes, wharfage, or
storage.[1767] For the purpose of determining wharfage charges, it is
immaterial whether the wharf was built by the State, a municipal
corporation or an individual; where the wharf is owned by a city, the
fact that the city realized a profit beyond the amount expended does not
render the toll objectionable.[1768] The services of harbor masters for
which fees are allowed must be actually rendered, and a law permitting
harbor masters or port wardens to impose a fee in all cases is
void.[1769] A State may not levy a tonnage duty to defray the expenses
of its quarantine system,[1770] but it may exact a fixed fee for
examination of all vessels passing quarantine.[1771] A State license fee
for ferrying on a navigable river is not a tonnage tax, but rather is a
proper exercise of the police power, and the fact that a vessel is
enrolled under federal law does not exempt it.[1772] In the State
Tonnage Tax Cases,[1773] an annual tax on steamboats measured by their
registered tonnage was held invalid despite the contention that it was a
valid tax on the steamboat as property.

KEEPING TROOPS

This provision contemplates the use of the State's military power to put
down an armed insurrection too strong to be controlled by civil
authority;[1774] and the organization and maintenance of an active State
militia is not a keeping of troops in time of peace within the
prohibition of this clause.[1775]

INTERSTATE COMPACTS

Background of Clause

Except for the single limitation that the consent of Congress must be
obtained, the original inherent sovereign rights of the States to make
compacts with each other was not surrendered under the
Constitution.[1776] "The compact," as the Supreme Court has put it,
"adapts to our Union of sovereign States the age-old treaty-making power
of independent sovereign nations."[1777] In American history the compact
technique can be traced back to the numerous controversies which arose
over the ill-defined boundaries of the original colonies. These disputes
were usually resolved by negotiation, with the resulting agreement
subject to approval by the Crown.[1778] When the political ties with
Britain were broken the Articles of Confederation provided for appeal
to Congress in all disputes between two or more States over boundaries
or "any cause whatever"[1779] and required the approval of Congress for
any "treaty confederation or alliance" to which a State should be a
par