The Congress pocket knife arrived on the scene in the early 1800s. A typical congress knife has a convex front with a shallow concave back, although there are a few that have straight backs. Most commonly it is made up of four blades. In modern times, a congress is usually used to describe a knife with 4 blades.
The early market for the knife was the Antebellum South and the blades chosen were those needed to fulfill its agricultural needs (tobacco, etc.). The most common Congress is the four blade pattern which features two large sheepsfoot blades as primary blades and small coping and pen blades as secondary blades. The sheepsfoot blades were used extensively in the cotton and tobacco industry. The reason for two sheepsfoot blades, one on each end, is the same reason the muskrat has two identical blades, it allowed the user to cut twice as long before having to stop and re-sharpen his blades. The coping blade was used for whittling, and the pen blade provided a blade with a point on it. There are 6-blade, 8-blade, 5-blade patterns, and even a half congress. There is a story that U.S. congressmen would be given whittling sticks to pass the time, so they wouldn’t carve into the furniture – maybe this is where the initial description of “a congress knife” came from.
The most famous congress is probably the six blade congress that Abraham Lincoln was carrying when he was assassinated. Today, many people call a 6-blade Congress, regardless of the blades configuration a Lincoln congress. The early Congress knives, including the Lincoln congress, were made on a slim concave shaped handle. This meant that when the knife was placed spine down on a flat surface only the ends would touch the surface; the center of the knife would be raised in the air.