The following highways are numbered 45:
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 A45 autoroute (proposed)
  A45 autoroute (proposed) National Highway 45 (India) (Grand Southern Trunk Road)
  National Highway 45 (India) (Grand Southern Trunk Road) Interstate 45
  Interstate 45  U.S. Route 45
  U.S. Route 45  Alabama State Route 45
  Alabama State Route 45  Arkansas Highway 45
  Arkansas Highway 45  California State Route 45
  California State Route 45  Colorado State Highway 45
  Colorado State Highway 45  Connecticut Route 45
  Connecticut Route 45  Florida State Road 45
  Florida State Road 45  Georgia State Route 45
  Georgia State Route 45  Georgia State Route 45 (former)
  Georgia State Route 45 (former) Idaho State Highway 45
  Idaho State Highway 45  Illinois Route 45 (former)
  Illinois Route 45 (former) Indiana State Road 45
  Indiana State Road 45  Iowa Highway 45 (former)
  Iowa Highway 45 (former) K-45 (Kansas highway) (former)
  K-45 (Kansas highway) (former) Louisiana Highway 45
  Louisiana Highway 45  Maryland Route 45
  Maryland Route 45  Massachusetts Route 45 (former)
  Massachusetts Route 45 (former) M-45 (Michigan highway)
  M-45 (Michigan highway)  Minnesota State Highway 45
  Minnesota State Highway 45  Missouri Route 45
  Missouri Route 45  Nebraska Highway 45
  Nebraska Highway 45  Nevada State Route 45 (former)
  Nevada State Route 45 (former) New Hampshire Route 45
  New Hampshire Route 45  New Jersey Route 45
  New Jersey Route 45  New Mexico State Road 45
  New Mexico State Road 45  New York State Route 45
  New York State Route 45  County Route 45 (Cattaraugus County, New York)
  County Route 45 (Cattaraugus County, New York)  County Route 45A (Cayuga County, New York)
  County Route 45A (Cayuga County, New York)  County Route 45 (Erie County, New York)
  County Route 45 (Erie County, New York)  County Route 45 (Genesee County, New York)
  County Route 45 (Genesee County, New York)  County Route 45 (Greene County, New York)
  County Route 45 (Greene County, New York)  County Route 45 (Herkimer County, New York)
  County Route 45 (Herkimer County, New York)  County Route 45 (Jefferson County, New York)
  County Route 45 (Jefferson County, New York)  County Route 45 (Niagara County, New York)
  County Route 45 (Niagara County, New York)  County Route 45 (Oswego County, New York)
  County Route 45 (Oswego County, New York)  County Route 45 (Otsego County, New York)
  County Route 45 (Otsego County, New York)  County Route 45 (Putnam County, New York)
  County Route 45 (Putnam County, New York)  County Route 45 (Rensselaer County, New York)
  County Route 45 (Rensselaer County, New York)  County Route 45 (Saratoga County, New York)
  County Route 45 (Saratoga County, New York)  County Route 45 (St. Lawrence County, New York)
  County Route 45 (St. Lawrence County, New York)  County Route 45 (Steuben County, New York)
  County Route 45 (Steuben County, New York)  County Route 45 (Suffolk County, New York)
  County Route 45 (Suffolk County, New York)  County Route 45 (Sullivan County, New York)
  County Route 45 (Sullivan County, New York)  County Route 45 (Ulster County, New York)
  County Route 45 (Ulster County, New York)  County Route 45 (Washington County, New York)
  County Route 45 (Washington County, New York)  North Carolina Highway 45
  North Carolina Highway 45  North Dakota Highway 45
  North Dakota Highway 45  Ohio State Route 45
  Ohio State Route 45  Oklahoma State Highway 45
  Oklahoma State Highway 45  Pennsylvania Route 45
  Pennsylvania Route 45  South Carolina Highway 45
  South Carolina Highway 45  South Dakota Highway 45
  South Dakota Highway 45  Tennessee State Route 45
  Tennessee State Route 45  Texas State Highway 45
  Texas State Highway 45  Utah State Route 45
  Utah State Route 45  Virginia State Route 45
  Virginia State Route 45  West Virginia Route 45
  West Virginia Route 45  Wisconsin Highway 45 (former)
  Wisconsin Highway 45 (former)| Preceded by 44 | Lists of highways 45 | Succeeded by 46 |