The costs of those industries which government units run on a commercial basis cannot be put in any of the previous classes. No net expenditure is expected to result, since the produce of the industry is calculated to equal or more than equal the expense, Examples, may be found in every political unit where industries have been undertaken by the state for the purpose of supplying commodities needed by the government, or for supplying them to individuals on a commercial basis. Reference to some of the preceding tables will show the importance of expenditures for public service enterprises.
Some of the more important materials which governments undertake to furnish for themselves are military and naval supplies. Transportation of goods, passengers, and messages is often supplied for individuals. Governments sometimes maintain monopolies, primarily for the sake of the revenue returns. Such are the tobacco and salt monopolies of some European states. Because of the revenue returns from this class of disbursements it does not occupy an important place in the consideration of public expenditures.