Voters could have as many as 15 ballot measures to sort through in November, but history suggests some proposals will fail to meet the threshold for signatures.

SALEM — Sponsors of proposed ballot initiatives have until Friday to turn in the required number of signatures to earn a spot on Oregon's fall ballot.

Voters could have as many as 15 ballot measures to sort through in November, but history suggests some proposals will fail to meet the threshold for signatures. Two years ago, 10 initiatives were submitted but two failed to get insufficient signatures, and voters rejected the eight that made it.

Proposed laws require 82,769 valid signatures; constitutional amendments, 110,358. The secretary of state has until Aug. 1 to verify the signatures.

More than 100,000 signatures already have been submitted on behalf of two measures. One would impose a 25-year prison sentence for repeat felony sex offenders and 90-day jail terms for third-time drunken-driving offenders. The other would authorize the Department of Human Services to license dispensaries under Oregon's 1998 medical-marijuana law.

Other initiatives including allowing a casino east of Portland, renewing the diversion of 15 percent of Oregon Lottery proceeds to parks and salmon habitat, and creating a panel of retired trial judges to draw new legislative-district lines after each census.

Through November 2008, according to the state Elections Division, Oregon voters have approved 118 of the 348 measures submitted to them by citizen petitions since initiatives began in 1902. The totals exclude legislative measures that opponents petitioned to refer to voters.

Twenty-five states allow some use of initiatives, although they vary by state. The leading states for initiatives are Oregon and California.

An analysis by the Initiative and Referendum Institute at University of Southern California indicates that nationwide use of the initiative has increased dramatically since 1978, when California voters approved Proposition 13, which limited property-tax rates and taxable values.

"That was the spark that lit the fire," said John Matsusaka, a USC professor of business and law. "Ever since then, we've seen heightened use of initiatives through the country."