Bumper-to-bumper highway congestion isn't just a modern phenomena. Rush hour traffic on the Oregon-California trail was just as bad -- probably worse.

The image of a lone wagon on the endless prairie is largely myth; it's more accurate to imagine a moving city. Many reported seeing wagons all the way to the horizon day after day.

And just like today's highways, there was quite a bit of jockeying for position. The goal was to get in front of the pack because anyone who was behind had to eat the billowing dust kicked up by the wagons ahead. Competition was fierce; those in the back often had to put on goggles just to see.

The crowded conditions got even worse in the evening when the wagons came together to camp. Many 49ers discovered that previous wagon trains had overgrazed the prairie, and so there was no remaining grass for the oxen and mules to graze. So it was not uncommon for 49ers to venture miles off the trail in the evening in search of grass for their animals.

A more serious consequence of all this crowding was poor sanitation. Each new wagon train dug their latrines near the previous group's -- and there was often leakage into the water supply. The result was illness and death.