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.
Mexico City Population 2017. Mexico City has a long, rich history and is know for being one of the largest financial centers in the continent and the largest Spanish-speaking city in the world. As of 2016, the population of the city is estimated to be 8.9 million. The estimated population of 8,918,653 in 2016 is up from 8.851 million in 2010.