Answer/Explanation:
“Gaining traction”, as used in the quoted statement of William A. Darity Jr., means becoming more popular as well as being supported widely.
In his statement regarding the arguments that support the restitution of ill treatment and injustice towards black Americans, most especially during the slave trade era, in an attempt to promote equity, he remarked that this argument is beginning to “gain grounds” simply as a result of technology today. Technology has helped in the push for reparation as information is very fast to disseminate today, people can easily check up histories and facts regarding slave trade, and thereby making more people far and wide to lend their support and voices.