I've watched a number of you-tube videos regarding set-up. I happened to be in Sam Ash this week and I noticed that on many guitars and across brand lines, the clearance between the 6th string and the first fret appears greater than the clearance at the first string, first fret. I can't believe that I never before noticed this or perhaps I need new eyes. The set-up videos on youtube do not mention graduated string clearances.

Can anyone shed some light on this? Thanks for your input.
The lower strings need more room to vibrate, so they're usually set ever so slightly higher than the higher strings.
"Air created the greenness. And once you've got something, that leads to otherness." - Karl Pilkington.
Note that clearance is measured from the bottom of the string, and thicker strings are therefore higher at their center.
Quote by federali
I've watched a number of you-tube videos regarding set-up. I happened to be in Sam Ash this week and I noticed that on many guitars and across brand lines, the clearance between the 6th string and the first fret appears greater than the clearance at the first string, first fret.
The e-1 string is lower end to end than the E-6.

Measuring across the 12th fret, the total clearance of the e-1 might ideally be on the order of .090 (90 thousandths of an inch. On the E-6, ideally you would measure something on the order of .100.

As was stated before, the overall string height is measured from the TOP of the 12th fret to the BOTTOM of whichever string you're measuring.

There are two other variables, neck relief, and nut height. (Which is what you where alluding to at the first fret).

The guitar is setup in this order:

1. Check, and/or set the neck relief.

2. Set the string height at the 12th fret.

3. AND only if it needs it (!), set the heights of the grooves. in the nut.

This last step has to be done conservatively and with great care , or you can really screw up your guitar!

Let Mr Becker show you how: http://thbecker.net/guitar_playing/guitars_and_setup/setup_page_01.html

Read the whole guide at least twice before you start. That will give you the best chance for success.