Reference

Tennessee API county codes

Every Tennessee API well number starts with 41, the state code. The next three digits are the county code, one of the 95 listed below, so a number beginning 41-001 belongs to a well in Anderson County.

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

How to read a Tennessee API number

41State: Tennessee
001County: Anderson
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 95 Tennessee counties

County code County API numbers start
001 Anderson 41-001-
003 Bedford 41-003-
005 Benton 41-005-
007 Bledsoe 41-007-
009 Blount 41-009-
011 Bradley 41-011-
013 Campbell 41-013-
015 Cannon 41-015-
017 Carroll 41-017-
019 Carter 41-019-
021 Cheatham 41-021-
023 Chester 41-023-
025 Claiborne 41-025-
027 Clay 41-027-
029 Cocke 41-029-
031 Coffee 41-031-
033 Crockett 41-033-
035 Cumberland 41-035-
037 Davidson 41-037-
039 Decatur 41-039-
041 DeKalb 41-041-
043 Dickson 41-043-
045 Dyer 41-045-
047 Fayette 41-047-
049 Fentress 41-049-
051 Franklin 41-051-
053 Gibson 41-053-
055 Giles 41-055-
057 Grainger 41-057-
059 Greene 41-059-
061 Grundy 41-061-
063 Hamblen 41-063-
065 Hamilton 41-065-
067 Hancock 41-067-
069 Hardeman 41-069-
071 Hardin 41-071-
073 Hawkins 41-073-
075 Haywood 41-075-
077 Henderson 41-077-
079 Henry 41-079-
081 Hickman 41-081-
083 Houston 41-083-
085 Humphreys 41-085-
087 Jackson 41-087-
089 Jefferson 41-089-
091 Johnson 41-091-
093 Knox 41-093-
095 Lake 41-095-
097 Lauderdale 41-097-
099 Lawrence 41-099-
101 Lewis 41-101-
103 Lincoln 41-103-
105 Loudon 41-105-
107 McMinn 41-107-
109 McNairy 41-109-
111 Macon 41-111-
113 Madison 41-113-
115 Marion 41-115-
117 Marshall 41-117-
119 Maury 41-119-
121 Meigs 41-121-
123 Monroe 41-123-
125 Montgomery 41-125-
127 Moore 41-127-
129 Morgan 41-129-
131 Obion 41-131-
133 Overton 41-133-
135 Perry 41-135-
137 Pickett 41-137-
139 Polk 41-139-
141 Putnam 41-141-
143 Rhea 41-143-
145 Roane 41-145-
147 Robertson 41-147-
149 Rutherford 41-149-
151 Scott 41-151-
153 Sequatchie 41-153-
155 Sevier 41-155-
157 Shelby 41-157-
159 Smith 41-159-
161 Stewart 41-161-
163 Sullivan 41-163-
165 Sumner 41-165-
167 Tipton 41-167-
169 Trousdale 41-169-
171 Unicoi 41-171-
173 Union 41-173-
175 Van Buren 41-175-
177 Warren 41-177-
179 Washington 41-179-
181 Wayne 41-181-
183 Weakley 41-183-
185 White 41-185-
187 Williamson 41-187-
189 Wilson 41-189-

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 Tennessee oil and gas regulator.

Frequently asked questions

What is the API state code for Tennessee?

41. 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 Tennessee API number?

Read digits three to five and find them in the table on this page. In 41-001-12345, the county code is 001, which is Anderson County. If the code is missing from the table, it is usually an offshore area rather than an onshore county.

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