Sky&Telescope's "Skygazer's Almanac" says latest sunset June 28th,
earliest
sunrise June 14. I think that's for latitude 40N.

40N lat is correct for those dates.

If I recall correctly, the sunset and sunrise curves are slightly out of
sync mostly because Earth's orbit is slightly elliptical.

I believe the elliptical orbit accounts for most of the offset. I would
imagine that adding the earths tilt into the equation adds something to it
too.

F Marion