A domicil needs no purpose. It is not necessary to justify your presence at your domicile. It is your permanent home

For jurisdictional purposes, namely the interstate commerce clause of the U.S. Constitution (Art. I, Sec 8, Clause 3), your claim of residency of a state is used to subject you to regulation under the interstate commerce clause.

BOUVIER's LAW DICTIONARY

Sixth Edition (1856)

RESIDENCE. The place of one's domicil. (q. v.) There is a difference between a man's residence and his domicil. He may have his domicil in Philadelphia, and still he may have a residence in New York; for although a man can have but one domicil, he may have several residences. A residence is generally tran-sient in its nature, it becomes a domicil when it is taken up animo manendi. Roberts; Ecc. R. 75.

2. Residence is prima facie evidence of national character, but this may at all times be explained. When it is for a special purpose and transient in its nature, it does not destroy the national character.

3. In some cases the law requires that the residence of an officer shall be in the district in which he is required to exercise his functions. Fixing his residence elsewhere without an intention of returning, would violate such law. Vide the cases cited under the article Domicil; Place of residence.

RESIDENT, international law. A minister, according to diplomatic language, of a third order, less in dignity than an ambassador, or an envoy. This term formerly related only to the continuance of the minister's stay, but now it is confined to ministers of this class.

2. The resident does not represent the prince's person in his dignity, but only his affairs. His representation is in reality of the same nature as that of the envoy; hence he is often termed, as well as the envoy, a minister of the second order, thus distinguishing only two classes of public ministers, the former consisting of ambassadors who are invested with the representative character in preeminence, the latter comprising all other ministers, who do not possess that exalted character. This is the most necessary distinction, and indeed the only essential one. Vattel liv. 4, c. 6, 73.

RESIDENT, persons. A person coming into a place with intention to establish his domicil or permanent residence, and who in consequence actually remains there. Time is not so essential as the intent, executed by making or beginning an actual establishment, though it be abandoned in a longer, or shorter period. See 6 Hall's Law Journ. 68; 3 Hagg. Eccl. R. 373; 20 John. 211 2 Pet. Ad. R. 450; 2 Scamm. R. 377.

Bouvier's Law Dictionary

14th edition, Vol. II, page 470

Residence indicates permanency of occupation, as distinct from lodging, or boarding, or temporary occupation, but does not include so much as domicil [sic], which requires an intention continued with residence. 19 Mc. 293; 2 Kent, Comm. 10th ed. 576.

Blacks Law Dictionary

4th Ed., Page 1176

"Residence" is not synonyumous with "domicile," though the two terms are closely related; a person may have only one legal domicile at one time, but he may have more than one residence. Fielding v. Casualty Reciprocal Exchange, L.App., 331 So.2d 186, 188.

In certain contexts the courts consider "residence" and "domicile" to be synonymous (e.g. divorce action, Cooper v. Cooper, 269 Cal.App.2d 6, 74 Cal. Rptr. 439, 441); while in others the two terms are distinguished (e.g. venue, Fromkin v. Loehmann's Hewlett, Inc., 16 Misc.2d 117, 184 N.Y.S.2d 63, 65).