Offenbach am Main (ˈɔfn̩bax ʔam ˈmaɪn) is a city in Hesse, Germany, on the left bank of the river Main. It borders Frankfurt and is part of the Frankfurt urban area and the larger Frankfurt Rhein-Main urban area. It has a population of 138,335 (December 2018). In the 20th century, the city's economy was built on machine-building, leather-making, typography and design, and the automobile and pharmaceutical industries. The inner city area of Offenbach is quite large and consists of the historic center of the city and its expansions of the 1800s. Three formerly independent suburbs were incorporated in the first half of the 20th century: Bürgel being the first in 1908, then Bieber and Rumpenheim in 1938 and 1942. South of the inner city area are the suburbs Lauterborn, Rosenhöhe and Tempelsee. Kaiserlei is a commercial district in the far west of the city bordering Frankfurt. In the west Waldheim is a residential neighborhood on the city limits with Mühlheim am Main. In 2010 the eastern part of the city center was officially named Mathildenviertel, as the area was already unofficially called by the locals. Unlike most larger cities in Germany, Offenbach was not completely divided into districts. Only the nine neighborhoods mentioned above were officially districts, leaving the largest parts of the city officially unnamed. Although specific names for neighborhoods and areas were already in use among the locals and residents. In June 2019 the city council approved a new act that subdivides the city's area entirely into 21 districts. The nine existing districts largely remained the same, most of them were even expanded. The new districts were laid out after the already by locals commonly known neighborhoods, such as the Westend, the Nordend or Buchhügel. A completely new name was only needed to be found for one neighborhood south of the city center, which never had commonly used name before: Lindenfeld. The name derived from an old name of a land lot in this area, when it was still fields in agricultural use prior to the 1800s.