If you’re concerned about your personal safety mixing it up with motorized traffic, your fears are not without merit. American roads are made for something powerful, weighty and full of horsepower. Stepping foot or pushing pedal upon them can indeed be daunting.
The tendency for the timid may be to ride on the sidewalk where things feel safer. Although permitted by law and seemingly intuitive, this is a big mistake. Because you are off-road, you are out of the line of sight for drivers and your risk of a collision goes way up (especially going in the opposition direction of adjacent traffic).
On a bicycle, you are safest when you are visible, following standard driving practices and behaving predictably as you ride. This is where bike lanes come in. Bike lanes are engineered to help facilitate predictability and act as a visual cue to separate bikes and cars.