Thanksgiving

 Igros Moshe (YD IV #11.4) Question Is celebrating Thanksgiving that is an American holiday prohibited because of the prohibition of bechukosayhem. For someone who wishes to participate in a special meal for the American secular day of thanks and gratitude – Thanksgiving which is treated as a type of holiday. Answer Since this is not listed amongst the religious holidays and there is no actual obligation to have a meal but it is merely a day of memorial for an event that happened long ago in America and signifies that he is happy to be in America – it would seem that it entails no prohibition either in the celebration with a meal nor with the specific custom of eating turkey.  We find a similar thing in the gemora that King Yannai made a celebratory meal for his military victories and he ate certain vegetables to memorialize the event. Nevertheless it is prohibited to establish it as an obligation or mitzva. But it should be viewed as an optional celebration. As long as it is not viewed as an obligation or mitzva it may be celebrated annually with a special meal.