I think what you're doing is over thinking listed elevations...as an example...if you drove from Houston to Denver the preferred route would be:
I 45 north to US287(just south of Dallas) all the way to Limon, Co. A elevation change of 5,000' and yet not encounter one grade...for the most part flat driving. When you see elevation listings for cities and towns rarely are there any immediate climbs to arrive at that location. You mentioned the El Paso elevation and seemed concerned with that, but there is no immediate grade/climb to get there.