The Earth Cargo Service (or ECS) was the primary operating agency governing the operations of Earth-registered interstellar cargo transport vessels in the first half of the 22nd century. It was governed by the Earth Cargo Authority. Ships needed a license to operate under the ECS, which in some cases could be lost if a rendezvous was missed. (ENT: "Broken Bow", "Horizon")
Prior to Starfleet's NX Project taking off with the launch of Enterprise NX-01 in 2151, ships of the Earth Cargo Service were Earth's only real presence in outer space. The crew of these ships would spend years traveling from one planet to another; whole generations of these "boomers" grew up in space, and the ownership of ships often passed down family lines.
Among the planets serviced by the Earth Cargo were Draylax, both Teneebian moons, Trillius Prime, Vega colony, Deneva colony, and presumably Earth. Trade also existed with the Demerians and the Orions.