Final answer:
You should signal at least 100 feet before making a turn in residential or city streets. On highways, signal even earlier to provide ample warning to other drivers.
Step-by-step explanation:
The appropriate distance to signal before making a turn is dependent on the driving regulations of the place where you are driving. However, a general rule of thumb that is commonly taught in driver's education is to signal at least 100 feet before you turn if you're driving in residential or city streets. On highways or at higher speeds, the distance should be greater to provide ample warning to other drivers. This facilitates enough reaction time for other drivers and helps prevent accidents.