Sunday is still considered the first day in Christianity. Jesus rising on the first day led to Christians celebrating the resurrection on Sunday and it eventually eclipsing the Saturday Sabbath. Also much of Latin America and Southern Africa also consider Sunday the first day of the week.

Mhh, yes. It seems you're right. Saturday is the day God rested supposedly?

Wow it really hasn't stuck. I stand corrected.

Ignoring the religious angle entirely, I've always thought it was weird that people consider Monday the first day of the week, because to me, Sunday and Saturday are at either "end" of the week, hence they are called "weekend" days.

If Monday is day 1, then Saturday is day 6 and Sunday is day 7, so Saturday is no longer a weekend.

(Yes, I know that you can argue it a different way such that it still makes sense with Monday as the first day of the week. But it just feels "wrong" to me, probably because I lived the first 15-20 years of my life without even knowing that anyone else didn't consider Sunday to be the first day of the week. Stuff you grow up with is hard to change.)

(Relatedly, no matter how hard I try, Celsius degrees never feel natural to me. Ditto for kilograms when talking about how much a human weighs. I've managed to get myself comfortable with meters and liters, at least, though I still sometimes have to "translate" in my head for things to make sense to me.)

At any rate, I do wonder when this difference solidified. Was Monday considered the first day of the week in western Europe during the period when Europe was colonizing pre-United-States? If so, when and why did the US (or colonists in the pre-US) switch to Sunday?

The argument I’ve heard against this is that Sunday is a week”end” day, not a week “start” day - here interpreting “end” as “terminator” rather than something like “bookend”

It is more logical for Monday to be first, because it comes right after end of the last week - week-end. The last two days are weekend - end of the week.

In Hebrew the days of the week are named numerically: first day, second day etc. Sunday is the first day of the week in israel. Saturday, the last day of the Hebrew week is the only one not named numerically, it’s called sabbath.

Mmmh…

Sunday is religiously the first day of the week (the Lord rises on “the first day of the week…” (John)).

It has become the “last day” only because people rest after their jobs (i.e. at the end of the “week”).

But conceptually, it is still the first day. It is indeed the First day of the new creation (Redemption).