The county, drawing on home sales during the past 12 to 18 months in which more and more sellers lowered their prices, reported it has trimmed residential assessments more than 10 percent on some properties.

The county's reduction in taxable values in single-family homes, condos and townhomes officially ends a cycle of rapid appreciation in the Las Vegas Valley, where home- owners saw their values jump by at least 10 percent every year for much of the decade, including approaching 40 percent two years ago. Overall, the county reported the average assessment dropped 2 percent to 3 percent in numbers certified Jan. 1.

Of the 590,000 residential parcels in Clark County, the assessor's office said about 85,000, or 14 percent, had their land values decrease. About 60,000 had the average value reduced by about 5 percent and 25,000 had declines averaging 10 percent, county officials said. There were a few reductions as high as 20 percent to 30 percent.

The lowering of the values by Clark County is the most tangible evidence to date that more and more homeowners are cutting prices to make a sale. The Greater Las Vegas Association of Realtors reported Monday that median price of existing homes sold in December was down 2 percent from December 2005.

And none of the statistics take into account incentives by homeowners who are offering to pay closing costs and provide other perks. That in essence further lowers the seller's return-on-investment.

"It means an overheated market is simply adjusting," said Richard Lee, vice president of First American Title, who said many investors are now willing to cut prices because appreciation is slowing. "It is as simple as that. It is coming back where it should be. The pendulum swings both ways. The consumer who has the power to write the checks is dictating where the market should be."

Home sales have been unable to keep pace with the swelling inventory that saw as many as 20,000 homes on the market during the latter half of 2006. High home prices, rising interest rates and a fear that prices will fall have kept many people from buying, which in turn has kept many potential new home buyers on the sidelines because they can't sell their existing homes.

The valuations are used by appraisers in determining values of homes on the market, and the reductions may mean banks won't be willing to finance homes for what some buyers are seeking, Lee said.

"This is definitely a trend for Realtors to say to sellers that 'you may not get as much money as you thought you would get in today's market conditions," Lee said. "If you want to sell, it has to be more competitive. You can get your price, but you have to wait a while.'"

The reduction in assessments have occurred throughout the Las Vegas Valley, including some areas where whole neighborhoods, like one in Anthem in Henderson, where 176 homes had their taxable values slashed by $30,000, said Rocky Steele, the county's assistant director of assessments. Most of the assessments are based on homes sales between July 1, 2005 and July 1, 2006 but some like the Anthem neighborhood were refigured based on sales over the last six months after a resident brought it to their attention, Steele said.

The drop in values, however, doesn't mean homeowners will pay lower property taxes, Steele said. A property-tax cap imposed by the Nevada Legislature in 2005 that limits tax increases to 3 percent a year is based on taxable values certified in 2004, Steele said.

Despite the declines in some neighborhoods, there are strong pockets in the Las Vegas Valley where values are continuing to increase, said Jeff Payson, the county's manager of appraisal.

The reduction in assessments nowhere approaches predictions of 20 percent to 30 percent some national analysts have forecast for Las Vegas. The Chicago Mercantile Exchange, which trades futures on housing prices, predicted Las Vegas will see its home prices fall 7.9 percent between August 2006 and August 2007.

Local analysts have been mixed on what they expect to see in the housing market in 2007. One analyst, Steve Bottfeld, vice president of Marketing Solutions, predicts there will be minimal price gains by the end of 2007.

Lee predicted there could be declines as high as 15 percent in some Las Vegas Valley neighborhoods during 2007. He said the key will be whether the inventory decreases or swells.

"It's Economics 101. The bigger the supply, the lower the prices and the shorter the supply, the higher the prices," Lee said.

Dennis Smith, the president of HomeBuilders Research, said he wouldn't be surprised if prices dropped 6 to 10 percent in 2007 on resale homes.

But he said this doesn't mean the end of an era of home appreciation in the Las Vegas Valley, although it won't reach 40 percent again. People will look back on what happened as a cycle because in some years home prices will drop 10 percent or they may rise 10 to 20 percent.

"That is realistic," Smith said of a 6 to 10 percent drop. "But you also have to say we had a 40 percent gain. It is still a positive over a three to four-year period. It is not like a crash model. The market is correcting, and this is the down part of the cycle. Some of these cycles can take 16 to 24 months to correct."

Smith noted that resale home prices appreciated 9.2 percent in 2001, 10.6 percent in 2002, 14.6 percent in 2003, 38.9 percent in 2004, and 14 percent in 2005.