_Varieties of Referendum._--The referendum may be obligatory or optional in character, that is, the approval of the electorate may be required by the constitution before certain laws shall go into effect, or the legislature in its discretion may refer a law to the people for their opinion. Thus the constitutions of many states declare that no law for increasing the debt of the state beyond a certain amount shall be valid until it has been submitted to the voters and approved by them. Again, the referendum may be mandatory or advisory in character. Under the mandatory form, the legislature is required to carry out the will of the electorate as pronounced on any subject referred to the voters, while the advisory referendum is nothing more than an expression of opinion which may or may not be followed by legislative action. Again, the referendum may be state-wide in its scope, as where a general law or question of public policy is submitted to the voters of the whole state, or it may be of a local character, as where a law affecting a particular community is referred to the voters thereof. The referendum as a device for adopting constitutions and constitutional amendments is as old as the republic itself, and is now the general practice (pp. 65, 70). In all the states except Delaware proposed amendments must be submitted to the voters at a general or special election, and must be adopted by them before going into effect. The use of the referendum for ordinary lawmaking is also an old practice, though it is much more generally resorted to now than formerly. Thus very early in our history it was employed for such purposes as the incorporation of towns, borrowing money, the location of county sites, division of counties, subscription to stock in railroads and other enterprises by states, counties, or towns, and the levying of special taxes for the support of schools. One of the important uses to which it was put was the determination of the question whether intoxicating liquor should be sold in a particular locality. In time what were called local option laws were passed in many states, giving the people of towns, cities, or other local divisions of the state the privilege of determining by popular vote whether liquor should be sold within their limits. Other matters that have frequently been made the subject of a referendum are: the granting of the suffrage to negroes, and sometimes the enfranchisement of women; the location of state capitals; the sale of school lands; the incorporation of state banks of issue; the granting of aid to railroads; the adoption of the township form of local government; the construction of canals; the erection of public libraries; and many other matters too numerous to mention. There is no state in which the referendum is not provided by the constitution for certain kinds of legislation, and there is hardly a general election held nowadays in which the voters are not called upon to pass judgment upon some proposed