Carolyn, the French word ‘trafic’ used to mean general vehicular movement etc is an anglicisme - an extension beyond the traditional French meaning of the word. 

Far and away the most common I hear is still ‘la circulation’ although I have heard ‘le trafic’ used by some native speakers, and on occasional radio reports. Whether this is generally representative of current usage or reflects my limited exposure I cannot say for certain. 

You will not go wrong with ‘la circulation’ but you may upset some ‘purists’ with ‘le trafic’. Ultimately if speaking with native speakers in your own circle, you can take a lead from them.

 

 https://www.dictionnaire-academie.fr/article/DNP0383

 https://www.larousse.fr/dictionnaires/francais/trafic/78916

 https://www.larousse.fr/dictionnaires/francais/trafic/78915