Good Morning Halliday,
I have to echo Christopher's comments, the assessed value has nothing at all to do with market value. The city assesses the basic measurements of the house and doesn't take into account many features that a house may or may not have, such as granite counters, which may add market value, but doesn't get factored into the assessment for taxation purposes. Same thing the other way just because a house has 4 bedrooms and 2 full baths, the assessment doesn't take into account that the house is in need of a complete rehab on the interior.
Hope that helps answer your question. If you feel that your assessment is unfair, you can file an appeal with the Tax Assessor. It can be a lengthy process, but could be worth it if you feel you are paying unfair taxes.