Why do we have Traffic Jams on Any of our State Expressways - LA, Chicago, etc? All we are doing is driving forward. Get with it & Move It !?

Because those roads aren't big enough to accommodate the number of cars on them at peak times.

One person driving slow on an already congested road slows the whole road down.

With each lane clogged, it becomes almost impossible for cars to change lanes to exit or to enter the highway without someone having to slow down.

If a lane gets closed due to construction, a break-down, or an accident, the problem is compounded even more, especially when most people don't comprehend how a zipper merge is supposed to work and don't let cars into their lane (or have to slow down too much to let a stopped car merge in).

It is a function of how much traffic is getting on and off. Between cars accelerating to get on and cars slowing to get off it results in other cars needing to adjust their speed. This produces an according effect where some cars might actually have to stop. There are also interchanges which do not have enough capacity for the traffic that is trying to use them.

The best solution is car pooling which can reduce the traffic to 1/3 the present rate. Public transportation is in many ways better but the cost savings is off set by the inconvenience of waiting.