Cross-border trade and population movement mean the Ugandan currency dominates the market, the Ugandan curriculum is taught in schools, Ugandan products are on sale everywhere, people listen to Ugandan FM radio stations and talk on Ugandan mobile phone networks. Thousands of people from the area still live in refugee camps in Uganda.
One Ugandan import, however, has brought nothing but fear, misery and death: the Lord's Resistance Army.
Nimule, its surrounding areas and roads, have been terrorised by the ambushes, looting and abductions by the Ugandan rebel group since the mid-1990s. The town hosts whole villages of people who have fled their home areas due to attacks by, or fear of, the LRA.
In addition, the town holds recently returned Sudanese refugees who had been living in camps in Uganda, and other long-term displaced communities that are unwilling or unable to return home, regardless of the LRA threat. But in addition to bustling commercial activity, there are social problems.
Nimule, situated at a bend in the Nile, is growing fast. A survey last year estimated the population at 45,000, but a local administrator, Shalfa Olweny Butrus, claims the town's population has doubled since.
The houses of displaced people - much like those in northern Ugandan camps - are scattered around the town, some on swampy land. Ugandan-style boda-boda motorbike taxis ply the dusty main street.
The latest community of displaced people to arrive in the town was already living temporarily in the Anzara settlement no more than a kilometre from Nimule. The Anzara people "originally came for safety - it turned out to be the opposite", said Gabriel Unzi Francis, a food monitor with the NGO Catholic Relief Services (CRS), which distributes food to Anzara and other needy communities in Nimule.
John Dick, a community leader from Anzara, said that on 20 February, two people were killed and three injured in a night-time raid.
Many households lost food and other property, he said. The settlement, not far from the Nimule airstrip, which is guarded by Ugandan and Sudan People's Liberation Army (SPLA) troops, has not been fully reoccupied, but people have started to go there by day, as security has stabilised for the time being, Dick said.
While Nimule does well from the constant flow of goods and people with Uganda, insecurity and displacement have left a diminished agricultural economy. The area could be very productive, according to agricultural workers, with crops including cassava, sweet potato, ground nuts and maize. But "people have deserted their fields" due to insecurity, Leonard Lagu of CRS told IRIN. It is a very difficult life for those who have to "depend on buying things from the market".
"We don't want to depend on this imported food," said Butrus. "When we see people depend on imported goods. I don't feel happy. If all become businessmen, who will buy?" he asked.
The roaring business atmosphere is also changing the social dynamics in the town and bringing new risks. Butrus is concerned about the rising number of bars and sex workers. "The worst enemy left is HIV," he said.
Drinking and inexperience contribute to a high number of traffic accidents on the improved road toward Juba. "All of them are learners," said Jeannot Wabulakombe, a doctor with the NGO Merlin, based in Nimule. In April and May, about 50 patients with serious traffic injuries were admitted to Nimule's hospital, one of the largest and best-run in Southern Sudan, soon to commission an X-ray machine.
Typical health problems in the area include malaria, which accounts for 40 percent of outpatients. Diarrhoea, a sign of poor sanitation and hygiene, can develop into a dangerous outbreak of cholera or acute watery diarrhoea and the hospital is continually on standby - "it can come back at any time", Wabulakombe said.
The population is so mobile, Wabulakombe continued, that programmes requiring extended treatment, such as TB, face particular problems.
Returnees from Uganda and IDPs
An SPLA commander in charge of patrolling the road north of Nimule, Bol Dur, said the return of refugees from Uganda would help security, denying the LRA the uninhabited space that suited their tactics and need for unhindered mobility.
Local administration officials are also keen for refugees in Uganda to return, but remain wary of the demands they will place on limited local services and anxious about land disputes. Many refugees in Uganda and IDPs congregating in larger settlements because of the LRA risk will not return unless peace between the LRA and the Ugandan government is assured. Even those who have already returned face problems adjusting.
The difficulties of rebuilding a life in Sudan are daunting, compared with the constrained but relatively predictable existence as a refugee in Uganda. As a local aid worker in Nimule said: "In Uganda, you get free food, you dig, you are peaceful."
Nimule hosts a large population of displaced people of Dinka origin, who fled the civil war in the Bor region of Jonglei, to the north, in the 1990s. An NGO survey in April 2006 indicated that more than 20,000 people living in Nimule - almost half the population - were of Dinka origin. Over 2,000 left voluntarily with assistance last year. But the most recent organised operation to help more return to Bor fizzled out, local sources say.
Some of them are occupying land that returnees expect to reclaim, a local official said. "They don't want to get out," he said, confirming that a recent attempt to truck Dinka communities back to Bor had failed: "The vehicle went empty," he said.
A September 2006 report compiled by UN and NGO agencies said a concerted effort was needed to "avoid a simmering violence" in Nimule.
Local people say resentment toward the Dinka is based not only on land, but also the fact that key positions in the military, police and customs are held by Dinka, not by people from the local area, where the Madi ethnic group dominates.