In all, there are 205 such measures on the November 7 ballots in 37 states. Ballot measures are proposed state laws that must be approved or rejected directly by voters within states. They can be placed on the ballot by legislatures, citizen petitions or other methods, and are often held in conjunction with general elections.

A measure in the conservative, sparsely populated state of South Dakota is perhaps the nation’s most momentous: Voters must decide whether to uphold or reject a new law banning abortions except when necessary to save a pregnant woman’s life. Activists on both sides of the national abortion debate see it as a historic test of public sentiment.

South Dakota lawmakers passed the ban in hopes that a subsequent court challenge might lead to the US Supreme Court overturning its 1973 Roe vs Wade decision legalising abortion. Instead of going to court, abortion-rights activists gathered enough petition signatures to put the measure to a statewide vote.

In Arizona, voters face 19 ballot measures, the most of any state, including one lottery-style proposal: As incentive for citizens to vote, it would award $1 million to a random voter in each general election.

Frustration over illegal immigrants also is huge in Arizona, which borders Mexico. Weeks after federal lawmakers approved a 1,125-km fence along the US-Mexico border, Arizonans will vote on four immigration measures: One would make English the state’s official language, another would deny bail to illegal immigrants charged with a serious felony.

The main event on Tuesday will be choosing 435 congressional representatives, 33 senators and 36 governors, many of whom have waged uncommonly hard-fought contests during a year when Americans say they are frustrated with the difficult war in Iraq and President George W. Bush’s dominant Republican party.

In many states, activists on the left and right hope turnout for certain ballot measures will have a spillover effect on crucial races in the battle for control of Congress. Liberals see a boost for Democrats if low-income voters mobilise on behalf of steps to raise the state minimum wage in Arizona, Colorado, Missouri, Montana, Nevada and Ohio.

Conservatives hope a court ruling last week in New Jersey that ordered equal rights for same-sex couples will trigger a backlash aiding Republican candidates in the eight states with ban-gay-marriage amendments on their ballots: Arizona, Colorado, Idaho, South Carolina, South Dakota, Tennessee, Virginia and Wisconsin.

Missouri is a battlefront in the debate over smoking; along with South Dakota and California, it has a hefty increase in tobacco taxes on its ballot. In California alone the two big tobacco majors, Philip Morris and R.J. Reynolds, have spent more than $56 million fighting a tax that would boost the average price of a cigarette pack to $6.55.

Even more money—a record of $133 million—has been raised in the fight over California’s Proposition 87, which would tax companies drilling for oil in the state to raise $4 billion to promote alternative fuels and energy-efficient vehicles. To compete against the oil companies, which have contributed more than $80 million, Hollywood producer Stephen Bing single-handedly gave $43 million o the environmentalist coalition supporting the tax.

Nevada and Colorado both offer measures that would legalise possession of up to 28 grams of marijuana by anyone 21 and older. A measure in Rhode Island would restore voting rights to felons on probation and parole.

In Michigan, voters will decide whether to bar the state from using affirmative action to determine who gets into college, who gets hired and who receives contracts. The measure, which comes just weeks before the US Supreme Court is to hear arguments in two cases that could mean big changes in federal affirmative action law, is opposed by the Democratic and Republican governor candidates and a slew of business, labour, educational and religious groups. But recent polls indicate it has a chance.