A cargo reminder for a driver of a vehicle includes an accelerometer, a controller to detect an acceleration change in the vehicle based on output signals from the accelerometer, and an alarm connected to the controller. Different types of alarm may be used, including a visual alarm, an audio alarm, a plug-in vibrator clip, or a combination of these alarms. In use, the alarm is triggered by the controller when the acceleration change is larger than a preset acceleration threshold. The cargo reminder may also include an acceleration threshold input to allow the driver to input the preset acceleration threshold, a delay setting input to allow the driver to input a time delay between first and second alarm triggers, and an inclinometer. A method for reminding the driver of a vehicle of an external cargo being transported is also within the scope of the instant invention.