In November, Natrona County voters may be asked approve or reject a temporary sixth-cent sales tax to help build a new library.

Before county residents see the measure on a ballot, four out of the six municipalities must give their approval, and that process is ongoing.

If approved, the measure would be the first application of the tax for a capital campaign.

Library officials have said they are seeking $43.25 million from the sales tax.

Here's a look at the differences between a fifth- and sixth-cent sales tax:

Fifth-cent sales tax: general use tax

* The current fifth-cent sales tax has been in Natrona County since 1976, said Casper City Manager Tom Forslund.

* Initially, Natrona County residents voted to reinstate the tax every two years.

* The fifth-cent sales tax is called a general use tax, and portions of the revenue are given to each of the county's six municipalities proportionate to population.

* Casper receives 74 percent of the fifth-cent sales tax revenue and uses it primarily to repair roads and water lines, Forslund said. The tax has also been used in Casper to help fund community projects such as the Fort Caspar Museum renovation, Platte River Parkway bridge and pumphouse, books at the county library, and an expansion at the Senior Center.

* It can be reinstituted by elected officials if they choose, but Forslund said that has never happened in Natrona County.

* The county is currently halfway through the 13th fifth-cent sales tax.

Sixth-cent sales tax: capital facilities or special purpose tax

* Natrona County residents have never approved a one-cent sales tax for capital facilities or special uses, said Casper City Manager Tom Forslund.

* There have been three proposals in the past, two for a new county courthouse and one grouping together several community projects.

* The Natrona County Public Library recently announced a plan to ask voters to approve a $43.25 million sixth-cent sales tax.

* Once $43.25 million is collected, the tax would end during the corresponding quarter. "I don't mean to make light of this," Natrona County Library Director Bill Nelson said in a recent meeting. "But if the tax doesn't stop, someone should put the state treasurer in jail."

* It will expire. The tax needs to be approved by the voters for the specified amount money can be collected.

* The sixth-cent optional sales tax cannot be reinstated by elected officials, Forslund said.

* If $43.25 million is not enough money to finish the project, the tax cannot be extended. In order to generate more sales tax money for a project, the process would need to begin again. This would include a new ballot measure followed by approval by the municipalities and the voters.

* Natrona County generates about $1.6 million each month by a one penny tax, Nelson said. If that rate continues, it will take roughly 27 months before the tax expires.

* Other counties in Wyoming have used this tax. Laramie County voters approved a $26.9 million measure in 2003.

Contact city reporter Christine Robinson at (307) 266-0639 or christine.robinson@trib.com