Other common causes of death included hypothermia, drowning in river crossings, getting run over by wagons, and accidental gun deaths. Later, more family groups started traveling, and many more bridges and ferries were being put in, so fording a dangerous river became much less common and dangerous. Surprisingly few people were taught to swim in this era. Being run over was a major cause of death, despite the wagons' only averaging 2–3 miles per hour. The wagons could not easily be stopped, and people, particularly children, were often trying to get on and off the wagons while they were moving—not always successfully. Another hazard was a dress getting caught in the wheels and pulling the person under. Accidental shootings declined significantly after Fort Laramie, as people became more familiar with their weapons and often just left them in their wagons. Carrying around a ten-pound rifle all day soon became tedious and usually unnecessary, as the perceived threat of natives faded and hunting opportunities receded.