John Navarre Macomb, Junior (1811–1889) was a United States Army topographical engineer and explorer of the Colorado River.

The expedition included the botanist and geologist John Strong Newberry, who made notable scientific observations along the route.

[1][2] Macomb was born on 9 April 1811 in New York City, and was the great-grandson of Philip Livingston, a signer of the Declaration of Independence.

The tri-point for the present states of Oklahoma, Colorado, and New Mexico is supposed to be the intersection between the 37th parallel north and the 103rd meridian west, where Macomb placed a monument in 1859.

I was directed, on my return to Santa Fé, to reduce my party and come in to Washington to prepare my report, and, on my way, to stop at the southwest corner of the Territory of Kansas, to set up a new monument at a point some two and a quarter miles to the east of the one originally placed there.