What a shock that would be to travel from the 1800s to today. I think the first thing that would shock me would be the spread of the community. There are many more people living in the US today than back in the 1800s. I think the architecture of the cities would be a shock. The height of the buildings as well as their girth would be impressive. The materials used to build the buildings would be a mystery.
The dress of the cities inhabitants would be interesting. Women wearing short skirts and skin revealing tops would definitely shock the time traveler.
Technology would be the most amazing change noticed. Being able to watch someone on television, talk on a phone, and use an elevator would be fascinating and even a little scary. I think the whole change would be frightening for anyone who traveled through time.
It would be a huge shock. First of all, the United States is much larger now. There were not as many states back then. If I were from 1850 I would have many questions about this.
Something else that would be very shocking is medical technology. Many more people died at an early age due to illnesses that are easily treated these days. Childbirth was a lot more dangerous as well.
Just a visit to a normal home would be amazing in itself because there are things like lights, plumbing, refrigerators, stoves, etc. They are all things that we take for granted but someone from the past would be absolutely amazed.
I would think that this world we live in today would be just about incomprehensible to a person from back then. I think that it would take a long time for them to even understand what is going on.
Think of all the things that would be beyond their comprehension. Cars would probably seem pretty normal since they sort of resemble carriages. But think of how they would react to airplanes and helicopters. Think of how they would look at all the people on their cell phones, especially the ones using those ear pieces.
When they go inside a house, think of how they will react. Electric lights. TVs. Vacuum cleaners. Dishwashers. All of this stuff would seem like magic.