Reference

Missouri API county codes

Every Missouri API well number starts with 24, the state code. The next three digits are the county code, one of the 115 listed below, so a number beginning 24-001 belongs to a well in Adair County.

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

How to read a Missouri API number

24State: Missouri
001County: Adair
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 115 Missouri counties

County code County API numbers start
001 Adair 24-001-
003 Andrew 24-003-
005 Atchison 24-005-
007 Audrain 24-007-
009 Barry 24-009-
011 Barton 24-011-
013 Bates 24-013-
015 Benton 24-015-
017 Bollinger 24-017-
019 Boone 24-019-
021 Buchanan 24-021-
023 Butler 24-023-
025 Caldwell 24-025-
027 Callaway 24-027-
029 Camden 24-029-
031 Cape Girardeau 24-031-
033 Carroll 24-033-
035 Carter 24-035-
037 Cass 24-037-
039 Cedar 24-039-
041 Chariton 24-041-
043 Christian 24-043-
045 Clark 24-045-
047 Clay 24-047-
049 Clinton 24-049-
051 Cole 24-051-
053 Cooper 24-053-
055 Crawford 24-055-
057 Dade 24-057-
059 Dallas 24-059-
061 Daviess 24-061-
063 DeKalb 24-063-
065 Dent 24-065-
067 Douglas 24-067-
069 Dunklin 24-069-
071 Franklin 24-071-
073 Gasconade 24-073-
075 Gentry 24-075-
077 Greene 24-077-
079 Grundy 24-079-
081 Harrison 24-081-
083 Henry 24-083-
085 Hickory 24-085-
087 Holt 24-087-
089 Howard 24-089-
091 Howell 24-091-
093 Iron 24-093-
095 Jackson 24-095-
097 Jasper 24-097-
099 Jefferson 24-099-
101 Johnson 24-101-
103 Knox 24-103-
105 Laclede 24-105-
107 Lafayette 24-107-
109 Lawrence 24-109-
111 Lewis 24-111-
113 Lincoln 24-113-
115 Linn 24-115-
117 Livingston 24-117-
119 McDonald 24-119-
121 Macon 24-121-
123 Madison 24-123-
125 Maries 24-125-
127 Marion 24-127-
129 Mercer 24-129-
131 Miller 24-131-
133 Mississippi 24-133-
135 Moniteau 24-135-
137 Monroe 24-137-
139 Montgomery 24-139-
141 Morgan 24-141-
143 New Madrid 24-143-
145 Newton 24-145-
147 Nodaway 24-147-
149 Oregon 24-149-
151 Osage 24-151-
153 Ozark 24-153-
155 Pemiscot 24-155-
157 Perry 24-157-
159 Pettis 24-159-
161 Phelps 24-161-
163 Pike 24-163-
165 Platte 24-165-
167 Polk 24-167-
169 Pulaski 24-169-
171 Putnam 24-171-
173 Ralls 24-173-
175 Randolph 24-175-
177 Ray 24-177-
179 Reynolds 24-179-
181 Ripley 24-181-
183 St. Charles 24-183-
185 St. Clair 24-185-
186 Ste. Genevieve 24-186-
187 St. Francois 24-187-
189 St. Louis 24-189-
195 Saline 24-195-
197 Schuyler 24-197-
199 Scotland 24-199-
201 Scott 24-201-
203 Shannon 24-203-
205 Shelby 24-205-
207 Stoddard 24-207-
209 Stone 24-209-
211 Sullivan 24-211-
213 Taney 24-213-
215 Texas 24-215-
217 Vernon 24-217-
219 Warren 24-219-
221 Washington 24-221-
223 Wayne 24-223-
225 Webster 24-225-
227 Worth 24-227-
229 Wright 24-229-
510 St. Louis city 24-510-

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 Missouri oil and gas regulator.

Frequently asked questions

What is the API state code for Missouri?

24. 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 Missouri API number?

Read digits three to five and find them in the table on this page. In 24-001-12345, the county code is 001, which is Adair County. If the code is missing from the table, it is usually an offshore area rather than an onshore county.

Does a Missouri 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). Missouri API county codes. Reference generated 2026-09-24. https://tetrasoftco.com/tools/api-county-codes/missouri/