The meridian 78° west of Greenwich is a line of longitude that extends from the North Pole across the Arctic Ocean, North America, the Atlantic Ocean, the Caribbean Sea, Panama, South America, the Pacific Ocean, the Southern Ocean, and Antarctica to the South Pole.

The 78th meridian west forms a great circle with the 102nd meridian east.

From Pole to Pole
Starting at the North Pole and heading south to the South Pole, the 78th meridian west passes through:

{| class="wikitable plainrowheaders"
! scope="col" width="120" | Co-ordinates
! scope="col" | Country, territory or sea
! scope="col" | Notes
|-
| style="background:#b0e0e6;" | 
! scope="row" style="background:#b0e0e6;" | Arctic Ocean
| style="background:#b0e0e6;" |
|-
| 
! scope="row" | 
| Nunavut — Ellesmere Island
|-
| style="background:#b0e0e6;" | 
! scope="row" style="background:#b0e0e6;" | Baffin Bay
| style="background:#b0e0e6;" |
|-
| 
! scope="row" | 
| Nunavut — Ellesmere Island
|-
| style="background:#b0e0e6;" | 
! scope="row" style="background:#b0e0e6;" | Baffin Bay
| style="background:#b0e0e6;" |
|-
| 
! scope="row" | 
| Nunavut — Bylot Island
|-
| style="background:#b0e0e6;" | 
! scope="row" style="background:#b0e0e6;" | Eclipse Sound
| style="background:#b0e0e6;" |
|-
| 
! scope="row" | 
| Nunavut — Baffin Island
|-
| style="background:#b0e0e6;" | 
! scope="row" style="background:#b0e0e6;" | Foxe Basin
| style="background:#b0e0e6;" |
|-
| 
! scope="row" | 
| Nunavut — Koch Island
|-
| style="background:#b0e0e6;" | 
! scope="row" style="background:#b0e0e6;" | Foxe Basin
| style="background:#b0e0e6;" |
|-
| 
! scope="row" | 
| Nunavut — Foxe Peninsula, Baffin Island
|-
| style="background:#b0e0e6;" | 
! scope="row" style="background:#b0e0e6;" | Foxe Channel
| style="background:#b0e0e6;" |
|-
| 
! scope="row" | 
| Nunavut — unnamed island just west of Mill Island
|-
| style="background:#b0e0e6;" | 
! scope="row" style="background:#b0e0e6;" | Foxe Channel
| style="background:#b0e0e6;" |
|-
| 
! scope="row" | 
| Nunavut — Nottingham Island
|-
| style="background:#b0e0e6;" | 
! scope="row" style="background:#b0e0e6;" | Foxe Channel
| style="background:#b0e0e6;" |
|-
| 
! scope="row" | 
| Nunavut — Digges Islands
|-
| style="background:#b0e0e6;" | 
! scope="row" style="background:#b0e0e6;" | Hudson Bay
| style="background:#b0e0e6;" |
|-
| 
! scope="row" | 
| Quebec — Ungava Peninsula
|-
| style="background:#b0e0e6;" | 
! scope="row" style="background:#b0e0e6;" | Hudson Bay
| style="background:#b0e0e6;" |
|-
| 
! scope="row" | 
| Quebec — Ungava Peninsula
|-
| style="background:#b0e0e6;" | 
! scope="row" style="background:#b0e0e6;" | Hudson Bay
| style="background:#b0e0e6;" |
|-valign="top"
| 
! scope="row" | 
| Quebec — Ungava Peninsula Nunavut — from , Frazier Island
|-valign="top"
| style="background:#b0e0e6;" | 
! scope="row" style="background:#b0e0e6;" | Hudson Bay
| style="background:#b0e0e6;" | Passing through the Salikuit Islands (at )
|-valign="top"
| 
! scope="row" | 
| Quebec Ontario — from 
|-
| style="background:#b0e0e6;" | 
! scope="row" style="background:#b0e0e6;" | Lake Ontario
| style="background:#b0e0e6;" |
|-valign="top"
| 
! scope="row" | 
| New York Pennsylvania — from  Maryland — from  West Virginia — from  Virginia — from  North Carolina — from  (passing just west of Wilmington at 34°14'N)
|-
| style="background:#b0e0e6;" | 
! scope="row" style="background:#b0e0e6;" | Atlantic Ocean
| style="background:#b0e0e6;" |
|-
| 
! scope="row" | 
| Island of Grand Bahama
|-valign="top"
| style="background:#b0e0e6;" | 
! scope="row" style="background:#b0e0e6;" | Atlantic Ocean
| style="background:#b0e0e6;" | Passing just west of the Berry Islands,  (at )
|-
| 
! scope="row" | 
| Island of Andros
|-
| style="background:#b0e0e6;" | 
! scope="row" style="background:#b0e0e6;" | Atlantic Ocean
| style="background:#b0e0e6;" |
|-
| 
! scope="row" | 
| Cayo Romano and the mainland
|-
| style="background:#b0e0e6;" | 
! scope="row" style="background:#b0e0e6;" | Caribbean Sea
| style="background:#b0e0e6;" |
|-
| 
! scope="row" | 
|
|-
| style="background:#b0e0e6;" | 
! scope="row" style="background:#b0e0e6;" | Caribbean Sea
| style="background:#b0e0e6;" |
|-
| 
! scope="row" | 
|
|-
| style="background:#b0e0e6;" | 
! scope="row" style="background:#b0e0e6;" | Pacific Ocean
| style="background:#b0e0e6;" | Passing just east of Gorgona island,  (at )
|-
| 
! scope="row" | 
|
|-
| 
! scope="row" | 
|
|-
| 
! scope="row" | 
|
|-
| style="background:#b0e0e6;" | 
! scope="row" style="background:#b0e0e6;" | Pacific Ocean
| style="background:#b0e0e6;" |
|-
| style="background:#b0e0e6;" | 
! scope="row" style="background:#b0e0e6;" | Southern Ocean
| style="background:#b0e0e6;" |
|-valign="top"
| 
! scope="row" | Antarctica
| Territory claimed by  (Antártica Chilena Province) and by the  (British Antarctic Territory)
|-
|}

See also
77th meridian west
79th meridian west

w078 meridian west
서경 78도(西經78度)는 본초 자오선에서 서쪽으로 78도 떨어진 경선이다. 북극점에서 시작하여 북극해, 북아메리카, 대서양, 남아메리카, 태평양, 남극해, 남극을 거쳐 남극점에 이른다.

서경 78도는 동경 102도와 이어져 지구의 둘레를 이룬다.

지나가는 지역 
북극점에서 남극점까지 서경 78도선은 다음 지역을 지나간다.

{| class="wikitable plainrowheaders"
! scope="col" width="120" | 좌표
! scope="col" | 나라, 지역, 해역
! scope="col" | 주석
|-
| style="background:#b0e0e6;" | 
! scope="row" style="background:#b0e0e6;" | 북극해
| style="background:#b0e0e6;" |
|-
| 
! scope="row" | 
| 누나부트 준주 — 엘즈미어섬
|-
| style="background:#b0e0e6;" | 
! scope="row" style="background:#b0e0e6;" | 배핀만
| style="background:#b0e0e6;" |
|-
| 
! scope="row" | 
| 누나부트 준주 — 엘즈미어섬
|-
| style="background:#b0e0e6;" | 
! scope="row" style="background:#b0e0e6;" | 배핀만
| style="background:#b0e0e6;" |
|-
| 
! scope="row" | 
| 누나부트 준주 — 바일롯섬
|-
| style="background:#b0e0e6;" | 
! scope="row" style="background:#b0e0e6;" | 이클립스 해협
| style="background:#b0e0e6;" |
|-
| 
! scope="row" | 
| 누나부트 준주 — 배핀섬
|-
| style="background:#b0e0e6;" | 
! scope="row" style="background:#b0e0e6;" | 폭스만
| style="background:#b0e0e6;" |
|-
| 
! scope="row" | 
| 누나부트 준주 — 코크섬
|-
| style="background:#b0e0e6;" | 
! scope="row" style="background:#b0e0e6;" | 폭스만
| style="background:#b0e0e6;" |
|-
| 
! scope="row" | 
| 누나부트 준주 — 배핀섬 폭스반도
|-
| style="background:#b0e0e6;" | 
! scope="row" style="background:#b0e0e6;" | 폭스 해협
| style="background:#b0e0e6;" |
|-
| 
! scope="row" | 
| 누나부트 준주 — 밀섬 바로 서쪽에 있는 이름없는 섬
|-
| style="background:#b0e0e6;" | 
! scope="row" style="background:#b0e0e6;" | 폭스 해협
| style="background:#b0e0e6;" |
|-
| 
! scope="row" | 
| 누나부트 준주 — 노팅엄섬
|-
| style="background:#b0e0e6;" | 
! scope="row" style="background:#b0e0e6;" | 폭스 해협
| style="background:#b0e0e6;" |
|-
| 
! scope="row" | 
| 누나부트 준주 — 디지스 제도
|-
| style="background:#b0e0e6;" | 
! scope="row" style="background:#b0e0e6;" | 허드슨만
| style="background:#b0e0e6;" |
|-
| 
! scope="row" | 
| 퀘벡주 — 언개버반도
|-
| style="background:#b0e0e6;" | 
! scope="row" style="background:#b0e0e6;" | 허드슨만
| style="background:#b0e0e6;" |
|-
| 
! scope="row" | 
| 퀘벡주 — 언개버반도
|-
| style="background:#b0e0e6;" | 
! scope="row" style="background:#b0e0e6;" | 허드슨만
| style="background:#b0e0e6;" |
|-valign="top"
| 
! scope="row" | 
| 퀘벡주 — 언개버반도 누나부트 준주 — 부터, 프래지어섬
|-valign="top"
| style="background:#b0e0e6;" | 
! scope="row" style="background:#b0e0e6;" | 허드슨만
| style="background:#b0e0e6;" | 살리쿠이트 제도()를 통과함
|-valign="top"
| 
! scope="row" | 
| 퀘벡주 온타리오주 — 부터
|-
| style="background:#b0e0e6;" | 
! scope="row" style="background:#b0e0e6;" | 온타리오호
| style="background:#b0e0e6;" |
|-valign="top"
| 
! scope="row" | 
| 뉴욕주 펜실베이니아주 — 부터 메릴랜드주 — 부터 웨스트버지니아주 — 부터 버지니아주 — 부터 노스캐롤라이나주 — 부터
|-
| style="background:#b0e0e6;" | 
! scope="row" style="background:#b0e0e6;" | 대서양
| style="background:#b0e0e6;" |
|-
| 
! scope="row" | 
| 그랜드바하마섬
|-valign="top"
| style="background:#b0e0e6;" | 
! scope="row" style="background:#b0e0e6;" | 대서양
| style="background:#b0e0e6;" |  베리 제도() 바로 동쪽을 지나감
|-
| 
! scope="row" | 
| 안드로스섬
|-
| style="background:#b0e0e6;" | 
! scope="row" style="background:#b0e0e6;" | 대서양
| style="background:#b0e0e6;" |
|-
| 
! scope="row" | 
| 카요로마노섬과 본토
|-
| style="background:#b0e0e6;" | 
! scope="row" style="background:#b0e0e6;" | 카리브해
| style="background:#b0e0e6;" |
|-
| 
! scope="row" | 
|
|-
| style="background:#b0e0e6;" | 
! scope="row" style="background:#b0e0e6;" | 카리브해
| style="background:#b0e0e6;" |
|-
| 
! scope="row" | 
|
|-
| style="background:#b0e0e6;" | 
! scope="row" style="background:#b0e0e6;" | 태평양
| style="background:#b0e0e6;" |  고르고나섬() 바로 동쪽을 지나감
|-
| 
! scope="row" | 
|
|-
| 
! scope="row" | 
|
|-
| 
! scope="row" | 
|
|-
| style="background:#b0e0e6;" | 
! scope="row" style="background:#b0e0e6;" | 태평양
| style="background:#b0e0e6;" |
|-
| style="background:#b0e0e6;" | 
! scope="row" style="background:#b0e0e6;" | 남극해
| style="background:#b0e0e6;" |
|-valign="top"
| 
! scope="row" | 남극
|  (안타르티카칠레나현)과  (영국령 남극 지역)이 영유권을 주장함.
|-
|}

같이 보기 
 서경 77도
 서경 79도

서경 078도