In Nevada, it's a percentage (approximately 0.5%, varying from city to city and with other conditions, like commercial usage) of its assessed value, which is 35% of taxable value. Taxable value is the market value of the bare land plus the replacement cost for all improvements on the land, less depreciation.
The cost of running a city is largely independent of house prices, so if the real estate market crashes there is no getting around that municipalities need to increase tax rates to meet their cashflow needs. People may not like that they feel they are getting ripped off, but the existing infrastructure has relatively fixed ongoing costs to maintain.
