Tuesday will be my first time flying out of LAS, and my first time flying Delta in probably 20 years. But that's besides the point.

I am taking an early morning flight (6am) and was planning on arriving 60 minutes before takeoff because of that instead of the usual 90... but I just noticed that I have to take a tram to get to the gates so I may need to bite the bullet and go to bed early.

Can I go through security at Terminal 3 (which looks closer via tram to D gates) even though my flight is departing from Terminal 1?

Yes you can.

I always go through T3 for Concourse D flights - it's easier to navigate than T1 anyway.

60 mins is plenty with PreCheck.

Update:

I arrived around 4:50am and had plenty of time. I got to the gate about 10 mins before boarding, but boarding starts so early that I would have been fine even if not.

This was the morning after Labor Day. The regular line was very, very long, easily 100-200 people and the drop off was pretty crazy. Precheck was very short so I made it through quickly. The terminal was very busy. Starbucks had a very long line. Lots of people running to catch flights. I was surprised at how busy it was at that hour, probably because of the holiday.

The tram was quick, but I was surprised at the walk (gate 38) and number of escalators. T1 would have taken even longer!

Hopefully next time I will have more time so I can explore. It's quite a nice airport.

T3 is a nice terminal and the D gates are pretty decent. I would in no way extrapolate that to say that LAS is "quite a nice airport."

(There is carpet in T1 that should have been replaced twice so far, yet it still hangs on.)

My kid spilled grape juice in T1 check-in area about 5 years ago on the carpet. That stain remained in place for the past 5 years. LAS airport has replaced all that carpet with terrazzo flooring in both arrivals and check in areas. Every time I walk past the spot Kettle1 Jr. spilled that grape juice, I get a tear in my eye. Memories.

For the inverse (Delta D gates to curbside), is Terminal 1 or 3 significantly better for the shuttle ride to the Rent-A-Car Center? Google maps suggests it's more of a straight shot from Terminal 1.

Thanks!

I'd say it's a minute or two difference, if that. And the quieter, newer, cleaner T3 makes it preferential to T1 all day.

Arrived last Thursday around 11 pm and took a moderately crowded tram to T3 and then walked to the Rental Car Shuttle pick up (pro tip - stay inside in the baggage claim and hang a left from the escalators until the end of the building so you don't have to walk outside in the heat). It's still a nicer experience than T1.

I took the 11 pm departure on Saturday night arriving at T3 around 9:30 and there was no line at PreCheck.

Clear is even faster than precheck. At time, the LAS T1 pre-check can be pretty long and Clear acts as a line pass. Not usually needed at T3 but can really helps at T1

T3 Pre can have a long line sometimes, although always better than T1 Pre IME. The idea of Clear is tempting, but it's a tough sell at $179 or even promo-coded at 149/yr though.

Delta SkyMiles member pricing starts at $99/year for non-status members.

https://www.clearme.com/partner/delta

Not saying it's necessarily worth it at that price point, but FWIW.