It is a very easy pattern and was originally made in blue and white so I decided to follow that tradition in my 6" block for my sampler quilt.
To make the Illinois Road block at 6" finished, you need four 2 1/2" squares and twenty 1" X 1 1/2" pieces of white fabric and twenty 1" X 1 1/2" pieces of blue fabric. You can also make strip sets using 1" strips of white and blue fabric. You need 30" of strips. It doesn't need to be all in one piece but it certainly can be.
I used 1" X 6" strips and cut them into four pieces as shown on the left below. These four pieces make a 2 1/2" four patch that is alternated with a 2 1/2" white square.
Illinois Road is a nine patch block that goes together like this-
The Illinois Road block can be found in Electric Quilt's Blockbase program as #1615.
I have not been able to find any old patterns or quilts made using the pattern.