What are the little funeral flags on hearses?

Funeral flags come in a range of colors, usually purple, but sometimes white, black, or orange. Typically affixed to the front of the hearse and vehicles within a funeral procession, these flags indicate that they are together (along with everyone's headlights on), and should not be interrupted by other drivers while on route to the burial site. Though federal or state laws may vary regarding whether or not a funeral procession is granted special privileges to disregard traffic control signals, New York's Vehicle and Traffic Laws require that emergency personnel be present if the procession is to do so.

Vinci v. Charney, 80 N.Y.S.2d 521 (N.Y. 1948).