AS TW muses, quintessence has many applications... so I have a different approach...
1. It's got to be private course, the "historical" essence of most of America's grandest courses, are private; and the whole enterprise was founded as a affluent game, not a public one. Though Pebble has a lot going for it, it doesn't have this...
2. It should be executed by an American designer... and it shouldn't have overt templates of European/UK holes, that's a deserved British parenting ethos, not an wholly American essence. In both takes, American essence is likely to be RTJ or Dye course, before a Mac or Raynor or a Ross or Mackenzie. Sawgrass is more American quintessence than NGLA, no? If not, I'll need your definition of quintessence.
3. Again, in "retention of original history" as essence, it's likely to be found in the regions of NY, Philly, Boston and Chicago; that's where it got started and got traction here...and whatever original essence is present, ought to be established longest there. And probably existing before 1930-35, when American course-building paused; an "essence" already having been built.
4. It'll be on parkland property, probably well-treed hilly parkland property. Though classics like Cypress and Shinnecock were developed in seaside/coastal sites, most American courses do not look or play like those and American course design is the advent and advertisement for the parkland course, isn't it, I don't think many here or abroad think "America" and summon CP and Shinny, nor do these courses broadcast anything particular typical or readily found on an "American" course.
5. It's likely to have in-course water to navigate and other midwifing of the aerial game...I mean, without wishing to forestall debate, aren't those American essences, that proliferated in US design, distinct to the UK home of the game?
6. Many, many great courses in America are widely known for their cost and difficulty and ingenuity to build, many times on ground usually unconsidered as golfing ground in UK venues; so I expect the qwintessential course to have been the result of a long or arduous, and/or imposing, perfectionist vision type of thing that cost bucks, that is still seen in how the course maintains and presents itself.
OK to take stock, if I keep to this criteria, I see these courses -- also with reputation enough -- to be American Quintessence
Myopia
The CC
Pine Valley
Merion
Medinah
Oakmont and Winged Foot would make it there if I didn't have a water criteria
As we loosen to later eras and/or other relaxing criteria...
Augusta National
Oakland Hills
Sawgrass
Southern Hills
Shadow Creek.
tri-Final Jeopardy Answer
1. Pine Valley - though it lacks a rich tournament hosting history, and we have to consider non American inputs, it's a big private, established, audacious, monumental site with hazards and singularity. There's no course like it and sprouts from the richest early corridor of course design.
2. Augusta National - if its critics re: Mackenzie's bastardization are correct, then it consciously stewarded the template for American parkland design. If those critics are wrong, then Mac was visionary enough to have seen what it would become.
3. Sawgrass - is anything more wholly representative of an original, influential, bright line American design than this?