So I am thinking about riding cross country this summer (don't worry, I've been planning)

I'm doing it on an awesome old Schwinn Voyageur touring bike.

I think my gearing for this ride will be:

28-38-48 chainrings

14-28 5 speed freewheel

I'm not planning on crossing the Rockies but I will be hitting Oregon (from Delaware). Has anyone used a similar gearing on this trip? I'm sure everyone who took it did before 1985....will I be kicking myself? Think I should go smaller on the inner ring? I don't feel like replacing the rear wheel as it is a nice 40 spoke rear wheel that has held up great to two years of commuting.

You'll be fine.

what about 22 /36 /48 far better, that 38 is to big if your fully loaded 36 middle ring up front is great

You are way ahead of where we were before our TA. We didn't have any idea we were going until 8 weeks before departure and it wasn't a sure thing yet for a few more weeks after that
Personally I would not find that gearing adequate, but others certainly have had higher. What route are you planning to take? Is it even possible to not cross the Rockies without being in the extreme southern part of the US? I didn't think so. In any case you will find LOTS of climbing on any coast to coast trip.

In the west I found 46-36-26 and 11-32 to be just adequate in the Cascades and Rockies and a littler higher than I would have liked in the worst spots in the steeper Appalachians. At the very least I would put on the smallest inner ring that fits your crankset. You can get one for about $12 so why not?

As an aside... we rode with a guy a bit on the TA. He was young and strong and was the first to the top of every climb despite running road gearing. He didn't make it through two states before he blew out his knee though.

You didn't ask about route or maps, but I will make a suggestion anyway. We found the Adventure Cycling maps to be a huge help and well worth the money. They contain much info about where to stay and where you can find all of the needed services. Post offices, stores, camping places, bike shops, motels, B&Bs, hostels, places of interest, and restaurants are all listed. The maps include info about the area, turn by turn directions, and profiles for the route in the western mountains.

I suggest taking one of their standard routes maybe the Northern Tier or the TransAmerica. Ether can be combined with the Lewis and Clark.

I will also plug my web page journal because we tried to document what we did and what did and didn't work well for us. The site is at:
https://www.crazyguyonabike.com/doc/staehling2007

If anything there raises any questions feel free to ask either here, in the journals guest book, or via email.

Have a great trip!

Thanks for the advice and the helpful links!

As for the Rockies I always forget that they extend in all directions up to Canada, they're just such a Colorado thing in my mind = ], can you tell I don't have the route completly planned yet haha?

Have fun with the planning and on the trip. Don't sweat the Rockies or the Cascades all that much other than to be sure you're gearing is adequate and you aren't carrying too much stuff. I found Virginia to be the hardest part of the trip. My two companions had never ridden in the mountains and loved the Rockies. We were all sad to leave them when we got to eastern Colorado (We rode West to East).