Way back when I started studying Spanish, I always learned that «in the morning/afternoon» was «por la manana/tarde». More and more lately (well, actually sometime shortly thereafter) I hear and read only «en la manana/tarde».

Does anybody still use «por» or is it always «en» nowadays?

I still see it listed in dictionary entries online and I am assuming these are current, in terms of their usage — although maybe that is a bad assumption. It seems I’ve been making a lot of those lately.

Any comments and opinions would be greatly appreciated. Thanks.