Yes, it almost surely is. Mine is currently traveling from Louisville to Washington, DC by ground - over 600 miles. UPS has always run a very tightly integrated operation. Anything traveling within 500 miles is usually trucked if the time exists. On a Second Day Air service, UPS can truck a package between nearly any two points east of the Mississippi, or up and down the West Coast.
FedEx, by contrast, historically ran a very fragmented operation. That's for a few reasons - it was mostly built through acquisition, whereas UPS grew organically, and FedEx was also designed from the ground up to be difficulty to unionize (only their pilots are unionized, versus nearly every aspect of UPS's operation). But a FedEx Express package traditionally never traveled via their ground routes, except in particular corridors where they ran dedicated Express trucks. UPS will put Next Day, Second Day, Three Day Select, and Ground all on the same truck if it makes sense, and they all go through the same sorting facilities. FedEx has separate facilities for Ground and Express. FedEx has been doing some integration of their two small package divisions over the last few years but it is nowhere near as integrated as UPS is. Few realize that FedEx Ground is almost entirely built on contractors - neither your FedEx Ground driver nor the driver who drives FedEx Ground trailers you see on the highway are FedEx employees (Express workers are all directly employed).