How long was the river Sidon? Knowing its length would be helpful in determining the location of the river and the scale of the land. The Book of Mormon account, unfortunately, only provides indirect evidence to answer this question. As we have noted, the “capital city which was the city of Zarahemla” was in the “center of the land” (Hel. 1:27). This places the city of Zarahemla more precisely than merely being somewhere within the interior. The land of Zarahemla was situated between the sea on the west and the sea on the east (Alma 22:28–29). Knowing the distance from the city of Zarahemla in the center of the land to these two seas would give a fair approximation of the length of the river Sidon, because its source or head would be part of the watershed divide between the two seas, somewhere near the city of Zarahemla.

There is an indirect way to estimate this distance: After the Nephites under king Mosiah (the first) joined with the people of Zarahemla, the record states many Lamanites were “driven” by the Nephites to the sea east “by the seashore” (Alma 22:29). At that time, Lamanites were also living “on the west of the land of Zarahemla, in the borders by the seashore” (Alma 22:28). How long or how far would the Nephites have continued to “drive” numerous resisting Lamanites from the center of the land to another location such as the sea east? One day, one week, one month? What was the purpose in driving them out of the Nephite lands other than placing some distance between them and the Lamanites? If the time or distance required to accomplish this task were too great, it would create a logistical supply problem for the Nephite pursuers and would vastly increase the chances the Lamanites at some point would simply disperse or outflank the Nephite forces and disrupt their mission. We suggest a pursuit distance measured by a two or three-day chase, certainly not many days or weeks. Assuming a travel distance of some 10 to 20 miles per day, this would place the center of the land of Zarahemla about 30 to 60 miles from each of the two seas. The length of the river Sidon, therefore, would be approximately this same extent.

There is another indirect way to estimate this distance: To the east of their land, the Nephites established a string of three cities—Aaron, Nephihah and Moroni—stretching in sequence from the city of Zarahemla in the center of the land to Moroni situated on the coast of the sea east (Alma 50:14; see also, Alma 8:13; 50:14; 51:22, 24; 59:5, 8; 62:25–26, 32; 3 Ne. 9:4). Not unlike the early Mormon settlements in Utah and elsewhere, we have noted the cities within the land of Zarahemla were located about 10 to 20 miles apart—about a day’s journey. Assuming the four cities of Zarahemla, Aaron, Nephihah and Moroni were aligned some 10 to 20 miles apart, this would yield a distance of about 30 to 60 miles from the city of Zarahemla in the center of the land to Moroni on the east coast. This somewhat uniform spacing of cities provides another way of estimating the length of the river Sidon—with its source at the center—at no more than 30 to 60 miles.

The Rio San Ignacio in Baja California has a direct length of some 30 miles from its head in the center of the peninsula to its mouth on the Pacific Ocean to the west, matching the relative scale of these implied distances. If we include the extension of the Laguna San Ignacio at the river’s mouth, the total length increases to more than 40 miles. And on the east, the head of the Rio San Ignacio is a distance of about 35 miles from the Sea of Cortez.