The municipality is composed of 6 parishes, and is located in the district of Setúbal.
The present Mayor is Alfredo José Monteiro da Costa, elected by the Unitarian Democratic Coalition and the President of the Municipal Assembly is Eufrázio Filipe Garcez José, also elected by the Unitarian Democratic Coalition.
The seat of the municipality is the city of Seixal which is crossed by the river from Lisbon. It is located in the district of Setúbal and next to the Rio Judeu ("Jew River"), the name given to a lagoon formed by the Tagus river.
The name "Seixal" comes from a type of smooth stone (seixo) that is found in rivers, and the city is named after these stones. The city was an important vacation resort for aristocracy from nearby Lisbon during the 1700s, namely in Quinta da Fidalga.
Seixal is also known for being one of the few cities in Portugal under the power of the communist party for 20 years.
The parish of Amora holds the yearly festival of the Portuguese Communist Party, that attracts hundreds of thousands of visitors. The events themselves consist of a three-day festival of music, with hundreds of Portuguese and international bands and artists across five different stages, ethnography, gastronomy, debates, a books and music fair, theatre (Avanteatro) and sporting events. Several foreign communist parties also participate.
Famous artists, Portuguese and non-Portuguese, have performed at the Festival, including Chico Buarque, Baden Powell, Ivan Lins, Zeca Afonso, Buffy Sainte-Marie, Holly Near, Johnny Clegg, Charlie Haden, Judy Collins, Richie Havens, Tom Paxton, The Soviet Circus Company, The L-Block Comerades, the Kuban Cossacks Choir, Dexys Midnight Runners, The Band, Hevia, Brigada Victor Jara, Adriano Correia de Oliveira, Carlos Paredes, Jorge Palma, Manoel de Oliveira and many others.
The preparation of the party begins right after the end of the previous festival. Hundreds of the Party's members and friends, mostly young people, volunteer for the hard work of building a small town in a few months.