Parcel Post
Congress approved a Stamp Act on August 24, 1912 that created postage rates on 4th class mail weighing 4 ounces or less at 1 cent per ounce or fraction. On mail over 4 ounces, the rate was by the pound. The rate for parcels of 4 ounces and over was to be prepaid by the new Parcel Post issues of 1913.

NOTE: The USPS produced 12 parcel post and  5 parcel post due stamps, usable only on parcel post packages starting January 1, 1913. Other stamps were not usable on parcel post starting on that date.

Beginning on November 27, 1912, the stamps were shipped to post offices offering parcel post service.

On July 1, 1913, the Postmaster General decreed that regular postage stamps would be valid for Parcel Post. Parcel Post stamps were then usable as regular stamps. Printing of Parcel Post and Parcel Post Due stamps was halted in 1913 and the remainder of these stamps were destroyed in September of 1921. 

NOTES: 
1. The 20c issue (Scott #Q8) was the first stamp in any country to depict an airplane.
2. Parcel Post Stamps were issued to Post Offices in 1912 and many were used for fourth class mail during December of 1912.

Special Delivery
Special Delivery service was instituted by an Act of Congress on March 3, 1885. The Act limited the service to Post Office's that served populations of 4000 or more until 1886 when they became available in all Post Offices. 

Special Delivery stamps ensured delivery during both daytime and evening at most post offices; thus the item did not have to wait until the next day for delivery. These stamps were in general use until 1957. 

Priority Mail and Express Mail are the methods in use today.