A number of States allowing first cousin Marriage Law in process only 4th Cousin Marriages shall be allowed Marriage to stop Child Abuse

Code of Ala. § 13A-13-3. Alabama appears to have no law voiding incestuous marriages, although § 30-1-3 does mention incestuous marriages being annulled.
Alaska Stat. § 25.05.021 (2010)
Alaska Stat. § 11.41.450 (2010)
A.R.S. § 25-101 (2010)
A.R.S. § 25-112 (2010)
A.R.S. § 13-3608 (2010)
In addition to statute, see In re Mortenson's Estate, 83 Ariz. 87, 316 P.2d 1106 (1957)
A.C.A. § 9-11-106 (2010)
A.C.A. § 9-11-107 (2010)
A.C.A. § 5-26-202 (2010)
See Etheridge v. Shaddock (PDF), 288 Ark. 481, 706 S.W.2d 395 (1986).
Cal Fam Code § 2200 (2010)
Cal Pen Code § 285 (2010)
Estate of Levie (1975, Cal App 1st Dist) was a California case on a purported first-cousin marriage contracted in Nevada. It found the marriage void per the usual rule.
C.R.S. 14-2-110 (2010)
C.R.S. 18-6-301 (2010)
Conn. Gen. Stat. § 46b-21 (2010)
Conn. Gen. Stat. § 53a-191 (2010)
13 Del. C. § 101 (2010)
13 Del. C. § 102 (2010)
13 Del. C. § 104 (2010)
11 Del. C. § 766 (2010)
D.C. Code § 46-401.01 (2010)
Fla. Stat. § 741.21 (2010)
Fla. Stat. § 826.04 (2010)
O.C.G.A. § 19-3-3 (2010)
O.C.G.A. § 16-6-22 (2010)
HRS § 572-1 (2010)
HRS § 707-741 (2010)
Idaho Code § 32-205 (2010)
Idaho Code § 32-206 (2010)
Idaho Code § 32-209 (2010)
Idaho Code § 32-501 (2010)
Idaho Code § 18-6602 (2010)
§ 750 ILCS 5/212 (2010)
§ 750 ILCS 5/213 (2010)
§ 750 ILCS 5/216 (2010)
750 ILCS 5/301 (2010)
720 ILCS 5/11-11 (2010)
In re Estate of Mary Kathrein was an Illinois Supreme Court case ruling that first cousins once removed are not to be confused with first cousins.
In addition to statute, see Meisenhelder v. Chicago & N.W. Ry. Co., 170 Minn. 317, 213 N.W. 32 (1927)
See In re Flores, 96 Ill. App. 3d 279, 51 Ill. Dec. 885, 421 N.E.2d 393 (1 Dist. 1981)
Chaper 595.19 Void Marriages
Burns Ind. Code Ann. § 31-11-1-2 (2010)
Burns Ind. Code Ann. § 31-11-8-3 (2010)
Burns Ind. Code Ann. § 31-11-8-6 (2010). Note that the laws listed do not pertain to cousin marriage.
Burns Ind. Code Ann. § 35-46-1-3 (2010)
See Mason v. Mason, 775 N.E.2d 706, 2002 Ind. App. LEXIS 1605 (2002).
K.S.A. § 23-102 (2009)
K.S.A. § 23-115 (2009)
K.S.A. § 21-3602 (2009)
Moore, A Defense of First-Cousin Marriage, 10 Cleveland Marshall L. Rev. 136 (1961)
See In re Estate of Loughmiller, 229 Kan. 584, where a foreign first cousin marriage was recognized in Kansas.
Kentucky Revised Statutes § 402.010 (2010)
KRS § 402.040 (2010)
KRS § 402.990 (2010)
KRS § 530.020 (2010)
Class B misdemeanor if marriage entered into; Class A misdemeanor if the couple cohabits after being convicted of entering into a prohibited marriage.
A marriage between first cousins will not be recognized in Kentucky even if it is consummated in another state. OAG 71-78.
La. C.C. Art. 90 (2010)
La. C.C. Art. 94 (2010)
La. R.S. 14:78 (2010)
See Ghassemi v. Ghassemi
19-A M.R.S. § 659 (2010)
19-A M.R.S. § 701 (2010)
17-A M.R.S. § 556 (2010)
Md. FAMILY LAW Code Ann. § 2-202 (2010)
Md. CRIMINAL LAW Code Ann. § 3-323 (2010)
ALM GL ch. 207, § 1 (2010)
ALM GL ch. 207, § 2 (2010)
ALM GL ch. 272, § 17 (2010)
"Michigan Marriage License Laws > MI Wedding Officiants". Retrieved 10 February 2013.
See In re Miller's Estate, 239 Mich. 455, 214 N.W. 428 (1927)
In addition to statute and preceding reference, see Toth v Toth (1973) 50 Mich App 150, 212 NW2d 812.
Minn. Stat. § 517.03 (2009)
Minn. Stat. § 518.01 (2009)
Minn. Stat. § 609.365 (2009)
Miss. Code Ann. § 93-1-1 (2010)
Miss. Code Ann. § 93-1-3 (2010)
Miss. Code Ann. § 93-5-29 (2010)
§ 451.020 R.S.Mo. (2010)
§ 568.020 R.S.Mo. (2010)
Mont. Code Anno., § 40-1-104 (2010)
Mont. Code Anno., § 40-1-401 (2010)
Mont. Code Anno., § 45-5-507 (2010)
R.R.S. Neb. § 42-103 (2010)
R.R.S. Neb. § 42-117 (2010)
R.R.S. Neb. § 28-702 (2010)
R.R.S. Neb. § 28-703 (2010)
Nev. Rev. Stat. Ann. § 125.290 (2010)
Nev. Rev. Stat. Ann. § 201.180 (2010)
RSA 457:2 (2010)
RSA 457:3 (2010)
RSA 639:2 (2010)
Prohibition of marriages between first cousins is applicable where the persons to be married are related only by adoption. 1987 Op. Att'y Gen. 46. (New Hampshire)
N.J. Stat. § 37:1-1 (2010)
N.J. Stat. § 2C:14-2 (2010)
N.M. Stat. Ann. § 40-1-7 (2010)
N.M. Stat. Ann. § 30-10-3 (2010)
NY CLS Dom Rel § 5 (2010)
NY CLS Penal § 255.25 (2010)
N.C. Gen. Stat. § 51-3 (2010)
N.C. Gen. Stat. § 14-178 (2010)
N.D. Cent. Code, § 14-03-03 (2010)
N.D. Cent. Code, § 14-03-08 (2010)
N.D. Cent. Code, § 12.1-20-11 (2010)
ORC Ann. 3101.01 (2010)
ORC Ann. 3105.31 (2010)
ORC Ann. 2907.03 (2010)
43 Okl. St. § 2 (2010)
21 Okl. St. § 885 (2010)
ORS § 106.020 (2009)
ORS § 163.525 (2009)
Oregon State Bar | http://www.osbar.org/public/legalinfo/1131_Marriage.htm
See Leefield v. Leefield, (1917) 85 Or 287, 166 P 953.
23 Pa.C.S. § 1304 (2010)
23 Pa.C.S. § 3304 (2010)
18 Pa.C.S. § 4302 (2010)
R.I. Gen. Laws § 15-1-1 (2010)
R.I. Gen. Laws § 15-1-2 (2010)
S.C. Code Ann. § 20-1-10 (2009)
S.C. Code Ann. § 16-15-20 (2009)
S.D. Codified Laws § 25-1-6 (2010)
S.D. Codified Laws § 22-22A-2 (2010)
S.D. Codified Laws § 25-1-38 (2010)
See Garcia v. Garcia, 25 S.D. 645, 127 N.W. 586 (1910)
Tenn. Code Ann. § 36-3-101 (2010)
Tenn. Code Ann. § 39-15-302 (2010)
Tex. Fam. Code § 2.004 (2010)
Texas Family Code, Title 1, Chapter 6, Subtitle B
Tex. Fam. Code § 6.201 (2010)
Tex. Penal Code § 25.02 (2010)
Utah Code Ann. § 30-1-1 (2010)
Utah Code Ann. § 30-1-4 (2010)
Utah Code Ann. § 76-7-102 (2010)
15 V.S.A. § 1a (2010)
13 V.S.A. § 205 (2010)
Va. Code Ann. § 20-38.1 (2010)
Va. Code Ann. § 18.2-366 (2010)
Rev. Code Wash. (ARCW) § 26.04.020 (2010)
Rev. Code Wash. (ARCW) § 26.09.040 (2010)
Rev. Code Wash. (ARCW) § 9A.64.020 (2010)
While no longer a criminal offense in Washington, prosecutions for sexual relations between cousins had taken place under a former statute. See State v. Nakashima, 62 Wash. 686, 114 P. 894 (1911).
Evasive marriages were held to be void in Washington even though there was no statute specifically making them such. See Johnson v. Johnson, 57 Wash. 89, 106 Pac. 500 (1910).
W. Va. Code § 48-2-302 (2010)
W. Va. Code § 48-2-303 (2010)
W. Va. Code § 48-2-503 (2010)
W. Va. Code § 48-3-103 (2010)
W. Va. Code § 48-2-602 (2010)
W. Va. Code § 61-8-12 (2010)
Wis. Stat. § 765.03 (2010)
Wis. Stat. § 765.04 (2010)
Wis. Stat. § 765.21 (2010)
Note that marriage abroad to circumvent the laws carries criminal penalties in Wisconsin; see Wis. Stat. § 765.30 (2010)
Wis. Stat. § 944.06 (2010)
Wyo. Stat. § 20-1-111 (2010)
Wyo. Stat. § 20-2-101 (2010)
Wyo. Stat. § 6-4-402 (2010)

Below image and color guide
Laws regarding first-cousin marriage in the United States

Purple - First-cousin marriage is legal

 Blue - Allowed with requirements or exceptions

 Pink - Banned with exceptions

 Red - Statute bans first-cousin marriage

 Brown - Criminal offense

Some states recognize marriages performed elsewhere, especially when the spouses were not residents of the state when married.^{clarification needed}

The future clarification is requirements to prove 4th Cousin to marriage in Federal Law of The United States of America