Rug warp is my backing of choice. It was sold to me as 60" but in reality you can count on 58″ 100% cotton. Threads per inch 11 x 13. I routinely hook wide cuts in this backing. If you have animals this is the backing to use. The loops are much more secure. Even my footstools are safe* from my cats. Order the number of yards you want. It will come in one piece that many yards long and 58″-60″ wide.
*Update: My son adopted a new dog when he was here for an extended visit. I think it stressed out my older cat. She began scratching so hard that a few tails have been pulled out. Minor damage, but not as “safe” as it was before. Now that the dog has gone home, she has stopped scratching so hard. After closer inspection, the wool is frayed, but the loops are still in place.