It has a land area of 719.34 km2, making it the smallest regency in East Java,[2] although it contains many of the southern suburbs of Surabaya and has a high population density.

(b) comprising 14 kelurahan (Bulusidokare, Celep, Cemengkalang, Gebang, Lemahputro, Magersari, Pekauman, Pucang, Pucanganom, Sekardangan, Sidokare, Sidoklumpuk, Sidokumpul and Urangagung) and 8 desa.

(c) comprising 8 kelurahan (Bebekan, Geluran, Kalijaten, Ketegan, Ngelom, Sepanjang, Taman and Wonocolo) and 16 desa.

Among this are : Jatim Taman Steel (Steel Manufacturer), Avian (Paints and building material), Tunggal Djaja (Paints Production), Maspion (Household durable goods), Japfa Comfeed (Feedmills and poultry), Interbat (Pharmaceuticals), Integra (Furniture), Tjiwi Kimia (Paper), Kimberly-Clark's Softex (Non-durable consumer goods), Unicharm (Non-durable consumer goods), Polygon Bikes (Bikes), Alumindo (Aluminium products), Sekar Group (Food processing), Hisamitsu (Pharmaceutical), Lighting Solutions (Lamp), ECCO (Footwear), Samator (Industrial gas and chemicals), Bernofarm (Pharmaceutical), Muntjul Diamond (Vehicle body), Charoen Pokphand (Agribusiness) and many more.

Garments, Food Processing, Footwear, Apparel, and Furniture are products that usually produced by small and medium manufacturers in Sidoarjo.

Many small and medium manufacturers produces Traditional Herbs, Machinery, Packaging, and Metal products.

[8] Gas and hot mud started spewing from the well on May 28, when the drill penetrated a layer of liquid sediment.

While some scientists have speculated that the earthquake that struck Yogyakarta on May 27, the day before the well erupted, may have cracked the ground, creating potential pathways for the mud to reach the surface, others have suggested that the drilling procedure was faulty by not using a casing.

[9] On September 26 barriers built to hold back the mud failed, resulting in the flooding of more villages.

Gus Maksum, one of the thousands of Sidoarjo villagers displaced by the mud flow gives a detailed first-hand account of the first year of the disaster in his memoir Titanic Made By Lapindo.