do turn signal lights have to be yellow
Automotive lighting The colour of light emitted by vehicle lights is largely standardised by longstanding convention. It was first codified in the 1949 Vienna Convention on Road Traffic and later specified in the 1968 United Nations Convention on Road Traffic.[5][6] With some regional exceptions, lamps facing rearward must emit red light, lamps facing sideward and all turn signals must emit amber light, while lamps facing frontward must emit white or selective yellow light. No other colours are permitted except on emergency vehicles.
Yellow line (road marking) Some parts of the US use a doubled set of double yellow lines to demarcate a painted median strip, which vehicles are not permitted to cross. This differs from a single set of double yellow lines, which may be crossed in certain circumstances.[14]