Today's school buses have been designed for better crash and rollover protection. They protect kids through "compartmentalization," which means spacing seats close together, as well as using seats with high, energy-absorbing backs to prevent children from being tossed around in a collision.

School buses are also highly visible and have safety features like red flashing red lights, cross-view mirrors and stop-sign arms. Drivers stay on carefully planned routes and maintain slow speeds, so seat belts aren't needed. That's the thought, anyway.

Unfortunately, though, deadly school bus crashes happen. Such was the case in November 2016 when a crash in Chattanooga, Tennessee killed six elementary school students. After another deadly school bus crash in May 2018 in Morris County, New Jersey, killed two, including a child, and injured 43 others, the National Transportation Safety Board opened a full investigation into school bus safety.

However, today seat belts are only federally mandated on small school buses, or those weighing 10,000 pounds or fewer. States are allowed to decide whether to mandate them by law on the rest of school buses. Currently, only eight states have laws requiring seat belts on large school buses, though many others are considering similar legislation.

Since most school buses are on the road for at least 10 and often up to 20 years, it's unlikely school districts would choose to retrofit older buses at that cost, which means it would potentially take decades for new legislation requiring seat belts to take effect across a fleet as new buses slowly replace older ones.