Colorado has the second fastest growing rate of child poverty in the nation, according a Kids Count Colorado, an annual report from Colorado Children’s Campaign.

The report, part of the Anne E. Casey Foundation’s national Kids County project, found that the rate of children living in poverty almost doubled between 2000 and 2011, to 18 percent from 10 percent, a trend experts say could get worse as the state slowly recovers from recent economic recessions.

Only Nevada’s child-poverty rate increased more quickly.

Released on Monday, the report, using data from the U.S. Census Bureau, found an average of one in six — about 217,000 — children under age 18 are living in poverty in the state. Colorado’s child poverty rate reached 18 percent in 2011, up from 17 percent in 2010.

“The trend is what we think is so troubling,” said Chris Watney, president of Colorado Children’s Campaign.

The largest single-year increase in the percent of children living in poverty was between 2000 and 2001. In that year, the child poverty rate increased from 10 to 13 percent, about 39,000 children. From 2008 to 2009 the child poverty rate climbed from 15 to 17 percent, about 31,000 children, making it the second largest single-year increase.

The two spikes correlate with recent recessions, Watney said.

Child poverty is defined as any child living in a four-person home with an average annual income of $22,000 or less. The study ranked the state’s 25 most populated counties.

Pueblo and Denver counties had the highest rate of child poverty. Pueblo’s average rate for 2011 was 27.3 percent and Denver’s was 26.2 percent. Douglas County continues to have the lowest child poverty rate, averaging 5.2 percent.

The average rate of child poverty for the 10 metro counties was 16. 1 percent.

Child poverty continues to increase in areas where the economy has been weak for decades, such as in some rural areas, but child poverty persists and presents new challenges in areas less familiar with the issue, such as Jefferson and Arapahoe counties, Watney said.

Jordan Steffen: 303-954-1794, jsteffen@denverpost.com or twitter.com/jsteffendp