The SS Conestoga was an Earth colony ship that was in service with the Space Agency in the mid-21st century. Launched from Earth in 2069, only six years after Zefram Cochrane's warp flight, the transport's mission was the colonization of Terra Nova, a nearby class M planet. The Conestoga was capable of carrying approximately two-hundred colonists, and was equipped for long-term travel. The Conestoga was commanded by Captain Mitchell.
The Conestoga took nine years, traveling just above warp 1, to reach Terra Nova. Once the Conestoga reached the planet, in 2078, its modules were dismantled to form the colony's initial structures and buildings. (ENT: "Terra Nova")
The name Conestoga references the Conestoga wagon used by American settlers in the 1800s. Just like the modules of the SS Conestoga were used to build shelters, Conestoga wagons could be disassembled and used for building materials once the cross-country journey was complete.
The Conestoga was designed by John Eaves, who stated that the design of the bridge, "(...) was actually inspired by a cool 18 wheeler I saw that had giant wind deflectors all across the top of the cab...I wish I had taken a picture of it when I saw it on the road."  The CGI model of the design was built by Doug Drexler, "I fully built the Conestoga which was designed by John for "Terra Nova", although it was only seen as a still image."
According to Doug Drexler the design of the Conestoga was influenced by the old DY-100 class ("The central conning tower and the rotund mid section"), the SS Valiant model designed by Greg Jein for the Star Trek Chronology and the Leif Ericson Galactic Cruiser. 
In the video game Star Trek: Legacy, a very similar design appears named the Discovery-class. Though sharing many similarities with the Conestoga's design, there are some substantial differences, including the fact that the Discovery served as a small scout ship armed with basic forward firing pulse phase cannons.
Four ships were shown being of this class, including the Discovery (NCC-100), the Patton (NCC-101), the Nebraska (NCC-103), and the Niagara (NCC-110). They are portrayed as still being in service in 2159.