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Last week Swann held its semi-annual African American art sale. The $2.5m sale total reconfirmed the market's overall levels and the price levels of several of its most important artists. More important in terms of the growth of this collecting category, which includes many artists who also sell in the Contemporary art category, is the way the numbers have begun to confirm a new plateau of sales volumes and average prices.

As the chart below reveals, the year-over-year growth of the African American art market continues. The last peak in sales was 2011. The market reset in 2012. Since that time, it has risen steadily until it made a dramatic leap in 2015. Those annual results reflected a dramatic 60% rise in auction volume from 2014 to 2015. More than $2m in sales were added in that period. But some of that was fairly lumpy in the form of a single Norman Lewis painting that made $965,000 at auction in 2015.