The first Trade and Intercourse Act of July 22, 1790, was enacted "to regulate trade and intercourse with the Indian tribes." Indian historian Francis Paul Prucha writes of this legislation:
One of the first laws of the new American nation to deal with Indian matters, the act reads:
Continuing the pattern set in the Ordinance of 1786 and earlier colonial legislation, the law first of all provided for the licensing of traders and established penalties for trading without a license. Then it struck directly at the frontier difficulties. To prevent the steady erosion of the Indian Country by individuals who privately acquired lands from the Indians, it declared the purchase of lands from the Indians invalid unless made by a public treaty with the United States. To put a stop to the outrages committed against the Indians by whites who aggressively invaded the Indian Country, the act made provisions for the punishment of murder and other crimes committed by whites against the Indians in the Indian Country.
Section 1. Be it enacted . . . That no person shall be permitted to carry on any trade or intercourse with the Indian tribes, without a license for that purpose under the hand and seal of the superintendent of the [War] department, or of such other person as the President of the United States shall appoint for that purpose; which superintendent, or other person so appointed, shall, on application, issue such license to any proper person, who shall enter into bond with one or more sureties, approved of by the superintendent, or person issuing such license, or by the President of the United States, in the penal sum of one thousand dollars, payable to the President of the United States for the time being, for the use of the United States, conditioned for the true and faithful observance of such rules, regulations and restriction, as now are, or hereafter shall be made for the government of trade and intercourse with the Indian tribes. The said superintendents, and persons by them licensed as aforesaid, shall be governed in all things touching the said trade and intercourse, by such rules and regulations as the President shall prescribe. And no other person shall be permitted to carry on any trade or intercourse with the Indians without such license as aforesaid. No license shall be granted for a longer term than two years. Provided nevertheless, That the President may make such order respecting the tribes surrounded in their settlements by the citizens of the United States, as to secure an intercourse without license, if he may deem it proper.
Sec. 2. And be it further enacted, That the superintendent, or person issuing such license, shall have full power and authority to recall all such license as he may have issued, if the person so licensed shall transgress any of the regulations or restrictions provided for the government of trade and intercourse with the Indian tribes, and shall put in suit such bonds as he may have taken, immediately on the breach of any condition in said bond: Provided always, That if it shall appear on trial, that the person from whom such license shall have been recalled, has not offended against any of the provisions of this act, or the regulations prescribed for the trade and intercourse with the Indian tribes, he shall be entitled to received a new license.
Sec. 3. And be it further enacted, That every person who shall attempt to trade with the Indian tribes, or be found in the Indian country with such merchandise in his possession as are usually vended to the Indians, without a license first had and obtained, as in this act prescribed, and being thereof convicted in any court proper to try the same, shall forfeit all the merchandise so offered for sale to the Indian tribes, or so found in the Indian country, which forfeiture shall be one half to the benefit of the person prosecuting, and the other half to the benefit of the United States.
Sec. 4. And be it enacted and declared, That no sale of lands made by any Indians, or any nation or tribe of Indians within the United States, shall be valid to any person or persons, or to any state, whether having the right of preemption to such lands or not, unless the same shall be made and duly executed at some public treaty, held under the authority of the United States.
Sec. 5. And be it further enacted, That if any citizen or inhabitant of the United States, or of either of the territorial districts of the United States, shall go into any town, settlement or territory belonging to any nation or tribe of Indians, and shall there commit any crime upon, or trespass against, the person or property of any peaceable and friendly Indian or Indians, which, if committed within the jurisdiction of any state, or within the jurisdiction of either of the said districts, against a citizen or white inhabitant thereof, would be punishable by the laws of such state or district, such offender or offenders shall be subject to the same punishment, and shall be proceeded against in the same manner as if the offence had been committed within the jurisdiction of the state or district to which he or they may belong, against a citizen or white inhabitant thereof.
Sec. 6. And be it further enacted, That for any of the crimes or offences aforesaid, the like proceedings shall be had for apprehending, imprisoning or bailing the offender, as the case may be, and for recognizing the witnesses for their appearance to testify in the case, and where the offender shall be committed, or the witnesses shall be in a district other than that in which the offence is to be tried, for the removal of the offender and the witnesses or either of them, as the case may be, to the district in which the trial is to be had, as by the act to establish the judicial courts of the United States, are directed for any crimes or offences against the United States.
Sec. 7. And be it further enacted, That this act shall be in force for the term of two years, and from thence to the end of the next session of Congress, and no longer.
The second Trade and Intercourse Act, enacted on March 1, 1793, was designed to improve on the Trade and Intercourse act decreed three years earlier. The law was established in reaction to a report from President George Washington, who told Congress that the original act was not working and needed to be strengthened. As historian Francis Paul Prucha explains:
The  law was a considerably stronger and more inclusive piece of legislation than its predecessor of 1790. The seven sections of the earlier law were expanded to fifteen.
Part of the increase came from the new sections authorizing the president to give goods and money to the tribes to "promote civilization . . . and to secure the continuance of their friendship," and from a long section that aimed to stop horse stealing, but the bulk of the augmentation came from the detailed provision enacted to stop criminal attacks of whites against the Indians and irregular acquisition of their lands. This act, too, was a temporary one, having the same limitations as the first trade and intercourse act.
Thomas Jefferson, in his annual message in 1801, called for a permanent renewal of the several trade and intercourse acts that had been enacted in the previous congresses. Historian Francis Paul Prucha writes, "Accordingly, on March 30, 1802, a new trade and intercourse act became law. It was for the most part merely a restatement of the laws of 1796 and 1799, but by now the period of trial was over. The act of 1802 was no longer a temporary measure; it was to remain in force, with occasional additions, as the basic law governing Indian relations until it was replaced by a new codification of Indian policy in 1834."
Enacted on June 30, 1834, the Trade and Intercourse Act of 1834 was the last of several such federal acts to "regulate trade and intercourse with the Indian tribes, and to preserve peace on the frontiers." Running for thirty sections, the most important portion of the Act, Section 1, reads:
Be it enacted by the Senate and House of Representatives of the United States of America, in Congress assembled, That all that part of the United States west of the Mississippi, and not within the states of Missouri and Louisiana, or the territory of Arkansas, and, also, that part of the United States east of the Mississippi river, and not within any state[,] to which the Indian title has not been extinguished, for the purposes of this act, be taken and deemed to be the Indian country.
Note: The bracketed comma was added by the Supreme Court in the case of Bates v. Clark to clarify the legislation's meaning.
John L. WIlliams
Prucha, Francis Paul. 1970. American Indian Policy in the Formative Years: The Indian Trade and Intercourse Acts, 1790–1834. Bison Books, University of Nebraska Press.