We know that סדם was on the Jordan Plain (ככר הירדן), so the first step in trying to identify where סדם was is identifying the ככר itself.

The Daat Mikra Bible Atlas, under Kikkar: “Plain” (page 8), says that “scholars do not agree about the origin of the term. Some associate it with the shape of the area, which, seen from afar, resembles a round loaf of bread; others believe that it means a steeply walled valley.” The main part of the Jordan River flows from the Kinneret to the Dead Sea (where it ends). The fertile area on the banks of the river is relatively long and narrow, not round. If it is called “הככר” because of its shape, it must be referring to the part just north of the Dead Sea. However, in Melachim I (7:46) the area between סכות and צרתן is part of ככר הירדן, and that area is about halfway between the Kinneret and the Dead Sea, well above the “round” area. Nevertheless, over time the term may have expanded to include a larger area; this does not preclude it from originally being called “הככר” because of its shape.

We are told (Bereishis 13:10) that the ככר reached until Zoar, which is almost universally accepted to be just south of the Dead Sea; consequently the Jordan Plain must have extended below the Dead Sea. However, the expression “באכה” can mean either “until you reach” or “in the direction of.” If it means the latter, the expression “באכה צער” could just be telling us that the fertile part of the Jordan Plain referred to its most southern part (before the destruction), and not that Zoar was part of the Jordan Plain. Zoar being spared despite the Torah saying that “the entire Plain was destroyed” (19:25) indicates that it was not considered part of the Plain.

One of the strongest arguments for סדם being north of the Dead Sea is that Lot “lifted his eyes and saw that the entire Jordan Plain was fertile” (13:10), and from his location between Beis El and Ai, a southern location would not be visible. (Avraham could see the smoke of a destroyed סדם from חברון whether it was north or south of the Dead Sea, since חברון is parallel to the middle of the Dead Sea, and rising smoke is more easily visible.) It has been argued that Lot didn’t have to see סדם itself; he could have first gone to the northern part of the Jordan Plain and then traveled south to סדם (see 13:12). However, if סדם was south of the Dead Sea, why was the area north destroyed too? (See Rashi on 18:17, that God explained to Avraham why He was destroying land that would eventually belong to him; if the sinners were not in the north, God wouldn’t have ruined Avraham’s land.) And if the part that Lot could see was not destroyed, the Torah didn’t need to point out that it was only fertile before סדם was destroyed.

One of the strongest arguments for סדם being south of the Dead Sea is that Lot was able to reach צער as the sun rose (19:23) despite his leaving סדם at עלות השחר (19:15, see Rashi on 19:24). Around Pesach time (when סדם was destroyed) there is less than 1.5 hours between עלות השחר and הנץ החמה in that area, not enough time to travel from north of the Dead Sea to south of it. Nevertheless, the timeline is not from עלות השחר to הנץ החמה, as the destruction started in סדם and then spread to other areas, with Lot being protected until he reached צער. The Zohar (quoted by באר בשדה, explaining how Rashi on 19:24 could say the destruction started at עלות השחר if the מלאך told Lot that he couldn’t do anything until Lot reached צער) says that the destructive “rain” trailed just behind Lot as he fled (which is why his wife was destroyed when she turned around). Even though the פסוק implies that Lot entered צער as the sun rose, it could mean that the destruction behind him (which Avraham saw early that morning) had already taken place at sunrise.

Another strong argument for a southern location is Yechezkel’s harsh admonition of Yerushalayim (16:46), saying it was worse than שמרון, which “dwells to your left” (read: north) and סדם, which “dwells to your right” (read: south). The area just above the Dead Sea is parallel to Yerushalayim, so referring to סדם as being south indicates that it was south of the Dead Sea (or on the Lisan Peninsula). Nevertheless, the language of prophecy takes poetic license, so סדם may not literally be south of Yerushalayim, as long as it is south of שמרון. Besides, since the bottom of Eretz Yisroel is shaped like a “U,” the Dead Sea is the southern part of its eastern border, even if it’s parallel to Yerushalayim, which is not the south of the middle of the country.

In 2013, “Discovering the City of Sodom” was published. Co-authored by archeologist Dr. Seven Collins, it details his excavations at Tall el-Hammam, which is almost parallel to Yericho. It, along with some smaller cities around it, has a major destruction layer from the second half of the Middle Bronze Age that includes ceramic objects that melted in such fierce heat that they turned into glass.

Many have rejected Dr. Collins’ assertion that this was Sodom based on chronological issues. But chronology is somewhat fungible. Suffice it to say that the traditional chronology has the Exodus in the year 1313 BCE, which would put the destruction of סדם in the year 1714 BCE (Yitzchok was born 400 years before the Exodus and the destruction happened one year earlier), while the Middle Bronze Age in the Near East spanned the years 2000-1550 BCE. There’s enough overlap between the two to not dismiss it.

I would add that if the destruction at Tall el-Hammam was not the destruction of Sodom, there must have been two once-in-human-history events that occurred in the same area, within a relatively short period of time. That doesn’t seem very likely to me.

With archeological evidence of a Sodom-like destruction in a location within visual distance of Bei El, in the primary area of ככר הירדן, if I was drawing a map, I would put סדם just north of the Dead Sea, on the eastern side of the Jordan River. (But I would add a footnote.)

Rabbi Dov Kramer has even more to say on this topic; an article twice as long can be read at dmkjewishgeography.wordpress.com