I am thinking that that is Grandpa and Grandma away from the camera. Mom is on the right and Dad is taking the picture. The girl looks too young for boyfriend camping.

The lid does not belong to a pressure cooker (note the collapsible handle in the center rather than a relief stem) - this lid most likely belongs to a utensil tote for camping.

Man, I gotta stop falling in love with these Shorpy babes. Especially since they are, as a rule, deceased.

The girls' hair is definitely forward-looking (to the 1940s). My gut feeling though is that the older women look reasonably "with it." In other words they don't look like they'd be wearing styles dramatically out of date -- they'd simply not pick up on the latest change as it happens. Given that the car is '35, my expert opinion puts it at 39-40.

No one has mentioned the family dynamics of this photo: Mother, Aunt, Father, older daughter, younger daughter -- not the kind of campsite you put up and take down in a day, so probably has been set up in a campground for a week. The Uncle pulls out the camera on the day your leaving, and catches the youngest not wanting to leave the boy she met. Oldest daughter in a good mood 'cause they are going home, Mother tired of cooking and cleaning in the "rough," Father wanting to get home to see the game.

Enameled coffee pot, still in style at fashionable camping sites thirty years later. Nothing like the taste of coffee grounds roasted over an open fire.

Yes, and before milk cartons, paper plates, the whole "modern" picnic thing.

These campers don't know how lucky they are to have real flatware, NOT the current despicable, fragile and useless forks and knives with which they expect people to enjoy outdoor and party dining today. I plan to purchase several of the boyscout version of aluminum all-in-one camping utensils to stash in my car just to keep from getting perturbed and annoyed by those who offer only the flimsy, weak and unusable disposable junk. I find that nothing spoils the fun of a joyful gathering more than crappy utensils! (And you darn kids stay off my lawn).

[The white kind is flimsy and to be avoided -- blech. The full size clear Lexan or polycarbonate variety, on the other hand, I've found to be pretty good -- my flatware of choice for camping trips or patio barbecues. The cheap aluminum flatware in a lot of camping kits is soft and bendy, much inferior to the better plastic. Nice stainless flatware, of course, trumps them all as far as style and function go. - Dave]

It looks to me as if the dark haired girl on the left is giving the photographer bedroom eyes, while the girl next to her is mortified and trying to meld into the background. Dad looks resigned and tense, while the aunt on the end looks disgusted. Mom just looks at the photographer as if to say, "don't even go there". The dark haired girl looks quite hot to trot, I think. Anyone else see this whole scenario?

Looks like a half open can of hash? A box of biscuits and eggs. What was in the pressure cooker?

Quick! Someone identify that pressure cooker lid!

Judging by the clothing. Here's my thoughts:

The men's haircuts look like they are from the late 1930s, but men tend to be conservative about their hairstyles. (Women too, actually; you can often tell a woman's age by her hairstyle if nothing else.)

The older women have hairstyles suggestive of the 1930s (but see above) while the younger, undoubtedly more fashion conscious, women have hairstyles that are more casual versions of mid-forties. This could be because those styles are changing into late-forties styles, or it could be because camping is a fairly casual activity.

Casual clothes are always a bit hard to date but are often earlier than you would suppose, because one decade's casual clothes become the next decade's more formal or at least more general wear. Believe it or not, the tuxedo was once casual (hunting) clothing! So these are not everyday clothes of the '50s and '60s. They are earlier.

That bare-shouldered dress on the dark haired woman facing the camera is definitely later forties and not thirties. The "playsuit" started in the later thirties but that kind of sexy bare shouldered look for informal activities didn't really get going until after the war.

I never before noticed the remarkable similarity between the '35 Plymouth Deluxe (see it here) and the '37-38 Chevy Master DeLuxe (see it here). It's hard to distinguish in the images I linked, but both cars have the rings on the hood, the suicide doors, the little window in the rear, the elongated hood. The grille would be a giveaway, but it's not really visible, and if you can make out the hood ornament in the Yosemite picture, your eyes are far better than mine. I will defer to the '35 Plymouth identification, though, because the pillar between the doors is slightly more visible on the Plymouth, and the rear door hinge is higher on the Plymouth (and both of these are evident in the Yosemite picture). Good catch!

The car in the background is definitely a 1935 Plymouth Deluxe Four Door Sedan. The trim rings on the hood give it away. Although it is blurred you can vaguely see the round sailing ship hood ornament. I hope this helps.

The circles on the hood, door hinge locations and the windshield wipers point to a 1935 Plymouth Deluxe sedan.

Those long skinny ladies' watches would indicate the 1930s also.

A data point: the car in the background is either a 1937 or 1938 Chevrolet Master DeLuxe four-door touring sedan. The breeze has placed the hanging clothes in rather inopportune positions, covering some details that would make the year more conclusive. Given what I can see, my guess is it's a 1937 model year car. It's impossible to tell how old the car was when the picture was taken, so all I can offer with any certainty is that the picture dates from 1937 or later. (If only the newspaper on the table was legible.)

Mildred? Have you seen my keys?? We'll never get out of this darned park if I don't find those keys!