The "Go Big Or Go Home" is about running a "Special Transport" load from several origin cities. You will have an in-game email that lists the cities where you get loads from. If you do not have any DLCs, you will get a list of 15 (AZ,CA) for the base game as of 1.53v. If you have additional DLC, then you will also need to take loads from the new added cities. The email in-game should show you these as additional routes.
Yes, this gets harder as time goes on. But, once you have the achievement it stays yours - future DLCs will not remove your achievement. If you do this before buying DLC, then its only the base game loads. If you do it today (v1.53) with all content then its 75 loads.

Each city usually has two different loads to choose from with the same destination. You do not have to run both loads listed in the job board, just one from each of these cities. There are a growing number of exceptions where there are multiple destinations. Its the different destination city that makes the difference here. Where there are two destination names, you will need two jobs (even though you will see four choices). One for each destination.

1. The load for the city San Francisco listed in the email is one of the Oakland routes, so you need to run both Oakland routes.
   
2. Denver has two routes destinations. One to each of the destinations listed is needed.
   
3. Pueblo has two to four routes depending on the DLC you have activated. Two interstate jobs are required for the Colorado DLC, and an additional two if you also have the Kansas DLC.
   
4. Other starting locations with multiple routes are Laurel MT, Oakland CA, Stockton CA, Truckee CA

Most loads are withing state lines, with notable exceptions of two Colorado to Kansas items added in the 1.49 dlc update (you will need both DLC to take on these jobs).

The game does not track this achievement in any UI or on Steam. You have to keep track of this yourself. The only way to see what you have so far is to decrypt a save file and pour through the thousands of lines of data. Not recommended. The list below may provide a handy checklist for this purpose and is certainly easier. I did mine by state which gave me a sense of ongoing accomplishment as I churn through this grind.

Reviewing the in-game email that YOU receive at the time of starting a profile will give you a somewhat clear list of which loads are required. Updates and added DLC can add new routes that the original email does not include, but in such a case you will revieve an additional email showing the added routes. Make sure you have visited the origin city to be able to see the loads on the job board.

ARKANSAS per the in-game email (from) and job boards (to) 21Sep24

• Jonesboro to Hot Springs
  
• Little Rock to El Dorado
  
• Little Rock to Texarkana

ARIZONA

• Kingman to Flagstaff
  
• Phoenix to Sierra Vista
  
• Yuma to Tucson

CALIFORNIA

• Eureka to Redding
  
• Fresno to Bakersfield
  
• Los Angeles to San Diego
  
• Oakland to Fresno
  
• Oakland to Huron
  
• Oxnard to Barstow
  
• Truckee to Carson City
  
• Truckee to Oakland (for the service boat if you have no DLC ???)
  
• Sacramento to Modesto
  
• Santa Cruz to Santa Maria
  
• Stockton to San Francisco (Thanks Maurachi)
  
• Stockton to Huron

COLORADO

• Burlington to Lamar
  
• Denver to Colorado Springs
  
• Denver to Grand Junction
  
• Pueblo to Denver (Town of Limon hwys 70/287)
  
• Pueblo to Pueblo (Town of Trinidad hwys 25/160) Thanks to Nikki Nam - confirming 2 Pueblos needed
  
• Pueblo to Dodge City Kansas (2 DLCs needed)
  
• Pueblo to Marysville Kansas (2 DLCs needed)
  
• Sterling to Colorado Springs

IDAHO

• Boise to Grangeville
  
• Idaho Falls to Salmon [Challis]
  
• Lewiston to Sandpoint
  
• Twin Falls to Nampa

KANSAS

• Colby to Hutchinson
  
• Topeka to Pittsburg
  
• Dodge City to Emporia
  
• Wichita to Salina

MISSOURI

• Kansas City to Rolla
  
• Cape Girardeau to Springfield
  
• St. Louis to Kirksville

MONTANA

• Butte to Bozeman
  
• Havre to Lewistown
  
• Laurel to Billings (added during OK release)
  
• Laurel to Glendive
  
• Thompson Falls to Kalispell

NEBRASKA

• Lincoln to North Platte
  
• Norfolk to Omaha
  
• ScottsBluff to McCook

NEVADA

• Primm to Ely
  
• Winnemucca to Carson City

NEW MEXICO

• Artesia to Las Cruces
  
• Clovis to Hobbs
  
• Farmington to Raton
  
• Gallup to Raton
  
• Santa Fe to Socorro
  
• Socorro to Tucson Arizona

OKLAHOMA per in-game email (from) and job boards (to) 02Aug23

• Clinton to Guymon
  
• Lawton to McAlester
  
• Oklahoma City to Tulsa

OREGON

• Dalles to Salem
  
• Pendleton to Burns
  
• Portland to Newport

TEXAS per the in-game email (from) and job boards (to) 18Nov22

• Corpus Christi to Brownsville
  
• Del Rio to Van Horn
  
• Fort Stockton to Abilene
  
• Laredo to San Antonio (added during OK release )
  
• Longview to Galveston
  
• Lubbock to Odessa
  
• San Angelo to Dallas
  
• Wichita Falls to Amarillo

UTAH

• Provo to Price
  
• Salina to Cedar City
  
• Vernal to Salt Lake City

WASHINGTON

• Omak to Yakima
  
• Port Angeles to Aberdeen
  
• Seattle to Everett
  
• Spokane to Grand Coulee

WYOMING

• Casper to Gillette
  
• Cheyenne to Rock Springs
  
• Laramie to Rawlins
  
• Riverton to Jackson

There are 11 types of loads as of 1.45 and it does not matter which ones you carry for this achievement. But - while you are at it - check off each load you have carried to insure you get all 11 for the "Big in America" achievement.

THE SERVICE BOAT IS EXTREMELY RARE. DROP EVERYTHING AND TAKE THIS ONE IF YOU SEE IT!

• Service Boat
  
• Giant Silo
  
• Massive Tech Part
  
• Large Reservoir Tank
  
• Helicopter
  
• Huge Construction
  
• Haul Truck Hull
  
• Haul Truck Chassis
  
• Huge Tires (sic Tyres)
  
• Air Conditioner
  
• Turnkey House

Update 1.49 adds two new loads (it is not confirmed if these are now required)

• Wind turbine cargo
  
• Articulated hauler cargo

• Trucker AlcatraZ® has confirmed that turning off all DLC left him with the 11 loads for California and Nevada. If you lose or regain your stats once reinstating these DLC is not clear. But the achievement popped. V1.50 updates this to 14 loads.
  
• The SERVICE BOAT is hard to get. I ran mine from Portland with the Oregon DLC enabled. I see it listed today in game coming from Truckee California. It is there, just that it is an RNG annoyance.
  
• The delivery of special transport from the city is not available until you visit it. If you have some cites that are still dark, this will prevent you from getting those special transport loads. Thanks to trucker @Fele(BiH) for confirmation.