Reference

Mississippi API county codes

Every Mississippi API well number starts with 23, the state code. The next three digits are the county code, one of the 82 listed below, so a number beginning 23-001 belongs to a well in Adams County.

To decode a whole number, including the sidetrack and completion digits, paste it into the API well number decoder.

How to read a Mississippi API number

23State: Mississippi
001County: Adams
12345Well, unique within the county

The first ten digits identify one well. Two more digits can follow for a sidetrack, and two after that for a later completion. The county is the one where the well starts at the surface, so a horizontal well that crosses a county line keeps its surface county's code. A few state regulators assign the producing county instead, so the state record is the final word on a well near a boundary.

All 82 Mississippi counties

County code County API numbers start
001 Adams 23-001-
003 Alcorn 23-003-
005 Amite 23-005-
007 Attala 23-007-
009 Benton 23-009-
011 Bolivar 23-011-
013 Calhoun 23-013-
015 Carroll 23-015-
017 Chickasaw 23-017-
019 Choctaw 23-019-
021 Claiborne 23-021-
023 Clarke 23-023-
025 Clay 23-025-
027 Coahoma 23-027-
029 Copiah 23-029-
031 Covington 23-031-
033 DeSoto 23-033-
035 Forrest 23-035-
037 Franklin 23-037-
039 George 23-039-
041 Greene 23-041-
043 Grenada 23-043-
045 Hancock 23-045-
047 Harrison 23-047-
049 Hinds 23-049-
051 Holmes 23-051-
053 Humphreys 23-053-
055 Issaquena 23-055-
057 Itawamba 23-057-
059 Jackson 23-059-
061 Jasper 23-061-
063 Jefferson 23-063-
065 Jefferson Davis 23-065-
067 Jones 23-067-
069 Kemper 23-069-
071 Lafayette 23-071-
073 Lamar 23-073-
075 Lauderdale 23-075-
077 Lawrence 23-077-
079 Leake 23-079-
081 Lee 23-081-
083 Leflore 23-083-
085 Lincoln 23-085-
087 Lowndes 23-087-
089 Madison 23-089-
091 Marion 23-091-
093 Marshall 23-093-
095 Monroe 23-095-
097 Montgomery 23-097-
099 Neshoba 23-099-
101 Newton 23-101-
103 Noxubee 23-103-
105 Oktibbeha 23-105-
107 Panola 23-107-
109 Pearl River 23-109-
111 Perry 23-111-
113 Pike 23-113-
115 Pontotoc 23-115-
117 Prentiss 23-117-
119 Quitman 23-119-
121 Rankin 23-121-
123 Scott 23-123-
125 Sharkey 23-125-
127 Simpson 23-127-
129 Smith 23-129-
131 Stone 23-131-
133 Sunflower 23-133-
135 Tallahatchie 23-135-
137 Tate 23-137-
139 Tippah 23-139-
141 Tishomingo 23-141-
143 Tunica 23-143-
145 Union 23-145-
147 Walthall 23-147-
149 Warren 23-149-
151 Washington 23-151-
153 Wayne 23-153-
155 Webster 23-155-
157 Wilkinson 23-157-
159 Winston 23-159-
161 Yalobusha 23-161-
163 Yazoo 23-163-

County names are the US Census names for these codes. The API standard does not promise the two match, so we checked them against state well records. Across 35 states, where this table names a county it matched the one the agency recorded on 85,091 of 85,100 wells. Offshore state and federal waters use their own pseudo-county codes, which are not listed here.

Finding the well itself

The API number stops at the county. It does not hold the well's coordinates, lease, survey section or operator. Those sit in the well record, which you find by searching the full number in the state agency's system. Search it at the Mississippi oil and gas regulator.

Frequently asked questions

What is the API state code for Mississippi?

23. API state codes run alphabetically from 01 for Alabama to 49 for Wyoming, then 50 for Alaska and 51 for Hawaii. They are not the Census FIPS state codes, which is a common source of wrong lookups.

How do I find the county from a Mississippi API number?

Read digits three to five and find them in the table on this page. In 23-001-12345, the county code is 001, which is Adams County. If the code is missing from the table, it is usually an offshore area rather than an onshore county.

Does a Mississippi API number give the well's exact location?

No. The number stops at the county. Coordinates, the lease and the survey location are in the well record held by the state agency, which you search with the full API number.

State codes: American Petroleum Institute Bulletin D12A well numbering standard. County names: US Census county FIPS names, checked against state well records. Reference generated .

How to cite this page

Sources: American Petroleum Institute Bulletin D12A well numbering standard; US Census county FIPS codes.

TetraSoft. (2026). Mississippi API county codes. Reference generated 2026-09-24. https://tetrasoftco.com/tools/api-county-codes/mississippi/