We would go back to mid 20th century tech. We would electricity and running water as well as basic tv channels but no cell phones, Internet, big budget movies, fast food restaurant chains, etc.
Mid 20th century?
You'd likely be back in the 1800's. Who's going to be around to maintain power plants, substations, sewage authorities, water mains, and power lines? And that doesn't even get into the ridiculousness of thinking people are going to be around to run TV stations, maintain a cable signal, and air Buffy reruns.
Not to mention most of the nuclear reactors in the country which generate a great deal of the electricity would likely have shut down, or at worst, started to go into meltdown without proper maintenance.
Only way you have power is if your home runs on solar, wind, or you have a generator with a massive amount of gasoline. (which somehow Hershel's farm seems to.)
Have you ever seen the History channel series Life After People? Hydroelectric plants in particular would last quite a while without human action.
We only get about 6% of our electrical power from hydroelectric plants.
http://mapawatt.com/2010/11/29/where-does-u-s-electricity-come-from/
And even if the plant is producing power, who's going to be around to fix and maintain the substations, power lines, transformers, circuit breakers, etc?
The economy would be non-existent, money would become worthless. The people that are left aren't just going to pick up and go back to work. There's not much incentive to do anything but survive at that point.
