Fundamentally, momentum conservation is linked to invariance under space translations. See Noether's theorem. If you want to find a system that does not conserve momentum you should look for situations where space is not uniform, e.g. balls rolling on the surface of a bowl, a planetary system (when the dynamics of the sun is neglected), etc.
Socorro is a city in Socorro County in the U.S. state of New Mexico. It is in the Rio Grande Valley at an elevation of 4,579 feet (1,396 m). In 2012 the population was 8,906.
In September 1850, New Mexico became a territory of the United States. At the time, New Mexico encompassed what is now the states of New Mexico and Arizona. In 1850, the population of Socorro was only 543 people. This included 100 American soldiers who were soon moved to Valverde. The first military post built near Socorro was Fort Conrad, 30 miles (48 km) south of the town.