Fact check: Thin Blue Line flag has taken a prominent place at Trump ralliesAt issue: A Thin Blue Line flag that was prominently featured behind Trump at an Oct. 24 rally in Waukesha. That blue stripe is meant to symbolize police officers as the “thin blue line” between order and chaos. First the anti-Black Lives Matter flag flew outside his rallies, then beside the American flag. In a June 8 article by the Marshall Project, “The Short, Fraught History of the ‘Thin Blue Line’ American Flag,” Andrew Jacob, president of Thin Blue Line USA said: “The flag has no association with racism, hatred, bigotry. And the Thin Blue Line flag has become a prominent part of the pro-police Blue Lives Matter movement, which arose to counter the Black Lives Matter movement.