I’ve wondered this too. Why didn’t the Hebrew tradition of The Sabbath = Saturday carry over to Chistianity? Why does the calendar start with Sunday? Why doesn’t the “weekend” consist of Friday and Saturday?
You do know that the US doesn’t necessairly follow a Monday-Friday work week, right? All that’s requried for full-time employment is a 40 hour work week. Find yourself a job which has a compressed schedule and you can work 10 hour days, four days a week and have three-day weekends.
Since Christ was resurrected on a Sunday, the early Christians started calling Sunday “The Lord’s Day” and eventually began worshipping on Sunday to avoid confusion with the Jewish Sabbath.