According to Ballotpedia, an online encyclopedia of information about politics at all levels of government, in November, there are 154 statewide ballot measures in 35 state. (If you include measures voted on before the November 8 election, that number goes up to 162). 71 of these ballot measures were put on the ballot via citizen initiative rather than by vote of the state legislature.

Measures on the 2016 statewide ballots include the following issues area (many of which are controversial) –

(1) Marijuana 

(2) Gun Control

(3) Minimum Wage

(4) California will vote on a statewide plastic bag ban

(5) Maine will vote on an initiative for a new system of voting

So what are ballot initiatives and referenda and whose uses them?

According to the National Council of State Legislatures, an initiative is

a process that enables citizens to bypass their state legislature by placing proposed statutes and, in some states, constitutional amendments on the ballot. The first state to adopt the initiative was South Dakota in 1898. Since then, 23 other states have included the initiative process in their constitutions, the most recent being Mississippi in 1992. That makes a total of 24 states with an initiative process.

There are both direct and indirect initiative processes. In a direct initiative process, qualifying proposals go directly on the ballot. In an indirect system, the initiative is first submitted to the state legislatures who may act on the proposal. Depending on the state, the initiative question will go on the ballot if the state legislature rejects the proposal, submits a different one, or takes no action. In some states, the legislature may also submit a competing measure that will appear on the ballot alongside the original ballot proposal. States with an indirect process include: Maine, Massachusetts, Michigan, Mississippi, Nevada and Ohio. In Utah and Washington, there are processes in place for either a direct or indirect ballot initiative process.

A referendum, on the other hand,

is a general term which refers to a measure that appears on the ballot. There are two primary types of referenda: the legislative referendum, whereby the Legislature refers a measure to the voters for their approval, and the popular referendum, a measure that appears on the ballot as a result of a voter petition drive.

What are the differences between legislative and popular referenda?

Legislatures are often required to refer certain measures to the ballot for voter approval. For instance, changes to the state constitution must be approved by voters before they can take effect. Many state legislatures are also required by their state constitutions to refer bond measures and tax changes to the voters. Although this is not always the case, legislative referenda tend to be less controversial than citizen initiatives, are more often approved by voters than citizen initiatives, and often receive higher vote thresholds. Legislative referenda may appear on the ballot in all 50 states.

The popular referendum is a device which allows voters to approve or repeal an act of the Legislature. If the Legislature passes a law that voters do not approve of, they may gather signatures to demand a popular vote on the law. Generally, there is a 90-day period after the law is passed during which the petitioning must take place. Once enough signatures are gathered and verified, the new law appears on the ballot for a popular vote. During the time between passage and the popular vote, the law may not take effect. If voters approve of the law, it takes effect as scheduled. If voters reject the law, it is voided and does not take effect. 24 states have the popular referendum. Most of them are also initiative states.

The map below, provided by Ballotpedia, shows which states use ballot initiatives and referenda.

You can learn more about the history of initiatives and referenda in the United States here.