Onsøy is a peninsula and a former municipality in Østfold county, Norway. The administrative centre was Gressvik.

The parish of Onsø was established as a municipality January 1, 1838 (see formannskapsdistrikt). A part of Onsøy with 170 inhabitants was moved to the neighboring municipality Fredrikstad on 1 January 1968.

On 1 January 1994 the rest of Onsøy was incorporated into Fredrikstad. Prior to the merger Onsøy had a population of 12.923.

The Old Norse form of the name was Óðinsøy. The first element is the genitive case of the name of the god Odin, the last element is øy meaning 'island'. The former island was later turned into a peninsula because of post-glacial rebound.

Onsøy Church (Onsøy kirke) was built in 1877. The architect was Henrik Thrap-Meyer. The church is of Gothic Revival style and constructed of brick with has 375 seats. Onsøy Church is located in Fredrikstad parish. Jens Bjelke was buried in the churchyard.^[1]

Elingaard Manor (Elingaard herregård) is a manor house located on Onsøy. The current main building was erected in the Renaissance style and was completed early in 1749. The building was constructed on two floors and consists of a main wing and two side wings. Outside is a garden laid out by English model. The manor house was developed by Chancellor Jens Ågessøn Bjelke (1580–1659). Jens Bjelke, one of the wealthiest men in Norway, was the grandson of Jens Tillufssøn Bjelke and the father of Jørgen Bjelke. His elder son Admiral Henrik Bjelke (1615–83) inherited Elingaard Manor. Elingaard manor is currently operated as a museum.^[2][3][4]

Onsøy is a former municipality in the Norwegian county (fylke) of Østfold, in the region of Østlandet. Østfold was known from 1662 to 1919 as Smaalenenes county (amt). Currently it is part of the municipality of Fredrikstad, which was established in 1838 and merged with the municipality of Glemmen in 1964. A small portion of Onsøy was switched to Fredrikstad in 1968, and the remainder of Onsøy joined Fredrikstad in 1994, along with the municipalities of Borge, Onsøy, Kråkerøy, and Rolvsøy. From 1070 to 1968, Onsøy was a parish in the Oslo diocese; since 1969 it has been part of the Borg diocese. From 1559 to 1660 it was part of what was then known as Akershus county (len).

Coordinates are approximate.
Note that each map has a maximum number of listings it can display, so the map has been divided into parts consistent with the enumeration districts (tellingskrets) in the 1920 census. This map will include one farm (gaard) name per farm number; other farm names or subdivision numbers may exist.

Onsøy municipality, tellingskrets 1-4 from 1920 census

2km
1.2miles

40: Onsøy kirke

39

38

37

36

35

34

33

32

31

30

29

28

27

26

25

24

23

22

21

20

19

18

17

16

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

  

Farms:

1

1: Ørmenneset

2

2: Havnen

3

6: Ørmen sæter

4

8: Høyum

5

10: Mollestad

6

11: Krabberød

7

12: Svierød

8

13: Fosse

9

14: Ammundrød

10

15: Torbjørnrød

11

35: Kjølberg

12

36: Kjevelsrød

13

37: Ingulsrød

14

38: Strand nedre

15

39: Krabberød

16

16: Valle nordre

17

17: Ulvedalen

18

18: Valle sondre

19

19: Ørmenveien

20

20: Ek

21

21: Slottet

22

22: Skogen

23

23: Mossigrød

24

24: Mossig nordre

25

26: Mossighuset

26

27: Kolberg nordre

27

29: Kolberghuset

28

31: Torp

29

32: Skuggerødmyren

30

33: Borge mellem

31

34: Borge østre

32

40: Skaare

33

41: Skaare mellem

34

42: Skaare søndre

35

43: Dale

36

44: Ørebæk vestre

37

45: Ørebæk østre

38

46: Brekke

39

47: Hurrød

40

Onsøy kirke (church), built 1877

Tellingskrets (enumeration districts): 1: gaards 1-15 (lime); 2: Haredalen, gaards 35-39 (black); 3: gaards 16-34 (blue); 4: Åle gnr. 40-47 (green)

Onsøy municipality, tellingskrets 5-11

2km
1.2miles

36

35

34

33

32

31

30

29

28

27

26

25

24

23

22

21

20

19

18

17

16

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

  

Farms:

1

48: Græsvik

2

49: Hauge

3

50: Aale øvre

4

51: Aale nedre

5

52: Rød

6

53: Okseviken

7

54: Krosnes

8

55: Viker

9

56: Fjelle store

10

57: Dale lille

11

58: Langeteig

12

59: Elslet

13

60: Torgauten

14

61: Søstrene

15

62: Nøklegaard

16

63: Oksrød

17

64: Slevik østre

18

65: Mellegaard

19

66: Slevik vestre

20

67: Langgaard

21

68: Dyrød

22

69: Halvorsrød

23

70: Brekke

24

71: Fjelle lille

25

72: Stenakrød

26

73: Gløsen

27

74: Fuglesangen

28

75: Tvete østre

29

76: Tvete vestre

30

77: Kjenne østre

31

78: Kjenne vestre

32

79: Lere

33

80: Lilleng

34

81: Torp søndre

35

82: Lund store

36

83: Lund lille

Tellingskrets (enumeration districts): 5: Græsvik (lime); 6: Hauge (black); 7: Aale nedre og Rød (green); 8: Okseviken - Krosnes - Viker (red); 9: gaards 56 Fjelle store to 63 Oksrød (purple); 10: Slevik (teal); 11: gaards 74 Fuglesangen to 83 Sund lille (blue)

Onsøy municipality, tellingskrets 12, 14, 15

2km
1.2miles

44

43

42

41

40

39

38

37

36

35

34

33

32

31

30

29

28

27

26

25

24

23

22

21

20

19

18

17

16

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

  

Farms:

1

84: Øtne østre

2

85: Øtne vestre

3

86: Skollerød

4

87: Sanderup

5

88: Stene lille

6

89: Stene store

7

90: Hauge søndre

8

91: Hauge nordre

9

92: Gjølberg

10

93: Forsetlund søndre

11

94: Forsetlund store

12

95: Forsetlund nordre

13

96: Bossum søndre

14

97: Bossum mellem

15

98: Bossum nordre

16

99: Lund vestre

17

100: Huseby store

18

101: Huseby lille

19

102: Ellinggaard

20

103: Espesti

21

104: Ytterstad

22

105: Hankø

23

106: Rauø

24

107: Smauet

25

108: Haviken

26

109: Rød vestre

27

110: Gaustad nedre

28

111: Tvete østre

29

112: Engelsviken

30

113: Skontorp

31

114: Stene vestre

32

115: Manstad

33

116: Husløs søndre

34

117: Lervik

35

118: Skjælø

36

119: Husløs nordre

37

120: Berge

38

121: Kjære

39

122: Koret

40

123: Kallerød

41

124: Østenstad

42

125: Saltnes mellem

43

126: Solberg

44

127: Røtne

Tellingskrets (enumeration districts): 12: Stene (lime); 14: gaards 106 Rauø to 112 Engelsviken (black); 15: Manstad (blue)

Following are the farms in the Onsøy (formerly Smaalenes) municipality, as they are listed in O. Rygh's series Norske_Gaardnavne ("Norwegian farm names"), the Smaalenes volume of which was published in 1897. Here is a digital version of that volume: <[1]>

The farm numbers are used in some census records, and numbers that are near each other indicate that those farms are geographically proximate. Handwritten Norwegian sources, particularly those prior to 1800, may use variants on these names. For recorded variants before 1723, see the digital version of O. Rygh. Note that the 1920 census records mapped above may not match O. Rygh. Additional farm numbers missing from the O. Rygh record were found in the 1950 Draft Land Registry.

Farm names were often used as part of Norwegian names, in addition to the person's given name and patronymic or inherited surname. Some families retained the farm name, or toponymic, as a surname when they emigrated, so in those cases tracing a surname may tell you specifically where in Norway the family was from. This tradition began to change in the mid to late 19th century, and inherited surnames were codified into law in 1923.

• Borges, Grethe (2007) Elingaard : et gammelt herresete (Fredrikstad] : Fredrikstad museum) ISBN 978-82-90301-21-2
• Dag Jukvam / Statistics Norway (1999). "Historisk oversikt over endringer i kommune- og fylkesinndelingen".

59°15′N 10°51′E / 59.250°N 10.850°E / 59.250; 10.850