The following highways are numbered 78:
International
Australia
Waterfall Way – New South Wales State Route B78
China
Greece
Iran
Korea, South
- Gukjido 78
New Zealand
New Zealand State Highway 78 – New Zealand's shortest State Highway
Philippines
United States
Interstate 78
U.S. Route 78
Alabama State Route 78
County Route 78 (Lee County, Alabama)
Arizona State Route 78
Arkansas Highway 78
California State Route 78
Colorado State Highway 78
Connecticut Route 78
Florida State Road 78
Georgia State Route 78
Hawaii Route 78
Idaho State Highway 78
Illinois Route 78
Iowa Highway 78
K-78 (Kansas highway)
Kentucky Route 78
Louisiana Highway 78
Maryland Route 78 (former)
Massachusetts Route 78
M-78 (Michigan highway)
Minnesota State Highway 78
Missouri Route 78
- Missouri Route 78 (1922) (former)
Montana Highway 78
Nebraska Highway 78
Nevada State Route 78 (former)
New Hampshire Route 78
County Route 78 (Bergen County, New Jersey)
New Mexico State Road 78
New York State Route 78
County Route 78 (Chemung County, New York)
County Route 78 (Dutchess County, New York)- County Route 78 (Herkimer County, New York)
- County Route 78 (Jefferson County, New York)
- County Route 78 (Lewis County, New York)
- County Route 78 (Madison County, New York)
- County Route 78 (Monroe County, New York)
- County Route 78 (Montgomery County, New York)
- County Route 78 (Niagara County, New York)
- County Route 78 (Orange County, New York)
- County Route 78 (Steuben County, New York)
County Route 78 (Suffolk County, New York)
County Route 78 (Warren County, New York)
North Carolina Highway 78
Ohio State Route 78
Oklahoma State Highway 78
Oregon Route 78
Pennsylvania Route 78 (former)
Rhode Island Route 78
Tennessee State Route 78
Texas State Highway 78
Texas State Highway Spur 78
Farm to Market Road 78- Urban Road 78 (signed as Farm to Market Road 78)
Utah State Route 78
Vermont Route 78
Virginia State Route 78
Wisconsin Highway 78
Wyoming Highway 78
- Territories
- U.S. Virgin Islands Highway 78