The efficiency of the transportation system really depends on the city. New York, Washington D.C., San Francisco and a few other cities are known for their extensive systems to travel across the city. Some cities, such as LA, have some forms of transportation but aren’t that great.
Other cities, like Oklahoma, are sometimes called driving states, meaning that public transport is practically non-existent and you’ll need a car to get around.
If renting a car isn’t an option, Uber and Lyft are very popular taxi apps in the USA. The price can add up and cost a fortune though, so research your options before you head to your destination.