Reader Donna Bickford, who wrote us a guest column after correspondent Amanda Keener's recent stories on human trafficking, emailed us today that the Polaris Project has upgraded North Carolina from Tier 2 to Tier 1 status among the 50 states based on legislation to combat the problem.

There are an estimated 18,000 to 20,000 trafficking victims -- essentially modern-day slaves -- in the United States, and North Carolina is among the top 10 states where trafficking has been reported, according to agencies that work on the problem.

The Washington-based Polaris Project began tracking anti-trafficking laws in 2007 when only 28 states had anti-trafficking criminal statutes. As of July 31, the number of states with anti-trafficking criminal statutes, including the District of Columbia, has grown to 48 with sex trafficking offenses and 50 with labor trafficking offenses.

As of July 31, 2012, 21 states are now rated in Tier 1, up from 11 states in 2011. Tier 1 states have passed "significant laws" against trafficking. Twenty-eight states (55 percent ) passed new laws to fight human trafficking in the past year, according to the Polaris Project.