al</p></dd>

  <dt>violent</dt>
<dd><p>whether the book was challenged for violent material</p></dd>

  <dt>state</dt>
<dd><p>US state in which the challenge was made</p></dd>

  <dt>political_value_index</dt>
<dd><p>Political Value Index of the state (negative = leans Republican, 0 = neutral, positive = leans Democrat)</p></dd>

  <dt>median_income</dt>
<dd><p>median income in the state, relative to the average state median income</p></dd>

  <dt>hs_grad_rate</dt>
<dd><p>high school graduation rate, in per