Perishable food should not sit out for more than two hours, according to the USDA. When the room is hotter than 90°F, the limit drops to one hour.
The rule covers every perishable dish on the Thanksgiving table, not only the carved turkey. Stuffing, gravy, mashed potatoes and chilled salads count too. A dish does not get a fresh two hours each time someone refills a plate from it.
The limit comes down to what happens as hot food cools. A freshly carved turkey starts well above 140°F. At room temperature, it gradually drops into the 40°F to 140°F danger zone. Every minute it spends in that range adds to the risk.
A correctly cooked bird is not protected for the rest of the day. Reaching a safe internal temperature handles the bacteria that arrive on the raw meat. The risk after cooking is a different one. Clostridium perfringens is linked to cooked food kept warm for too long, and a platter left out through a long meal fits that description.
Holiday meals make the limit easy to overshoot. Guests come back for second helpings, then dessert, then more conversation. The serving dishes often stay out the whole time. Every one of those hours counts toward the same two-hour limit.
Hot dishes have a clear target. The USDA says to hold hot food at 140°F or above, the top edge of the danger zone. Warming trays and slow cookers can keep turkey, stuffing and gravy at that temperature through a long afternoon. Food held that hot stays above the danger zone instead of cooling into it.
Cold dishes need the opposite treatment. Salads, cranberry relish and other chilled sides should stay at 40°F or below, the bottom edge of the danger zone. A cold dish that warms up on the table enters the same range as a cooling turkey.
Any perishable dish that is not held hot or cold needs to leave the table before its two hours are up.