Me and myMy wife and I did the trip the other way round in May this year, we are from Europe. We had our passports and ESTA (USA) and ETA (Canada). We flew to and from Canada and visited Buffalo in the USA by car.
Entry procedures and traffic into the USA took maybe 30-45mins (at Niagra Falls) and we had to go inside the building to talk to the CBP officer. The other direction it was about 10min and we didn't need to get out of the car.