The government of Indiana Territory began July 4, 1800, as recorded in the opening entry of the territorial journal (Executive Journal of Indiana Territory, 1800-1816. - Indiana Historical Society publications, vol. iii).

The seat of government was Vincennes. The Governor was William Henry Harrison, and his three coworkers, the judges, were William Clarke, Henry Vanderburgh and John Griffin. John Gibson was Secretary of the territory and acting-governor on various occasions. Harrison himself did not arrive at Vincennes until January of 1801 and prior to that Gibson appointed a number of minor officials and attended to the necessary administrative matters.

One of Harrison's first acts was to convene his judges and proceed to adopt and publish laws for the territory, the resulting being a code of seven laws and three resolutions. These, chiefly, dealt with the levying of taxes, the practice of attorneys and of courts, the establishment of courts, the compensation of officers and the establishment of ferries (Dillon, pp. 409).

The territorial judges at Vincennes began the first session of the general court, on March 3, 1801, and the first grand jury was empanelled with nineteen members.