| Type | First Day Cover Stamp Envelope |
|---|---|
| Year | 1974 |
| Signed | No |
| Theme | Astronauts & Space Travel |
| Country of Origin | United States |
Check the listing for details. United States First Day Cover Stamp Envelope Skylab Project. Made in United States. Listed at 9.99 USD. Skylab served as a long-duration laboratory and was pivotal in proving humans could live and work in space for extended periods.