Designation as I-68 thumb|left|I-68/US 40 eastbound and US 219 northbound at MD 495 near Grantsville, Maryland Though the National Freeway was designated as US 48, as the completion of the freeway neared, the possibility of the freeway being designated as an Interstate Highway came up. In the 1980s, the project to improve US 50 between Washington DC and Annapolis to Interstate Highway standards had been assigned the designation of I-68. MDSHA, however, later concluded that adding additional route shields to the US 50 freeway would not be helpful to drivers since about half the freeway already had two route designations (US 50 and US 301) and drivers on the freeway were already familiar with the US 50 designation. This made the designation to be applied to that freeway more flexible, and so, in 1989, the American Association of State Highway and Transportation Officials (AASHTO), the organization composed of the various state departments of transportation that decides route numbering in the U.S., approved MDSHA's request to renumber the US 50 freeway from I-68 to I-595. That same year, AASHTO approved changing US 48's designation to I-68. This change took effect upon the completion of the last section of the National Freeway on August 2, 1991.
Designation as I-68 thumb|left|I-68/US 40 eastbound and US 219 northbound at MD 495 near Grantsville, Maryland Though the National Freeway was designated as US 48, as the completion of the freeway neared, the possibility of the freeway being designated as an Interstate Highway came up. In .the 1980s, the projec!t to improve US 50 between Washington DC and Annapolis to Interstate Highway standards had been assigned the designation of I-68. MDSHA, however, later concluded that adding additional route shields to the US 50 freeway would not be helpful to drivers since about half the freeway already had two route designations (US 50 and US 301) and drivers on the freeway were already familiar with the US 50 designation. This made the ,designation to be applied to that freeway more flexible, and so, in 1989, the American Association of State Highway and Transportation Officials (AASHTO), the organization composed of the various state departments of transportation that decides route numbering in the U.S., approved MDSHA's request to renumber the US 50 freeway from I-68 to I-595. That same year, AASHTO approved changing US 48's des.ignation to I-68. This change took effect upon the completion of the last section of the National Freeway on August 2, 1991.