Editing Ain (section)

== Geography ==
[[File:SNCF TGV PSE Viaduc de Cize - Bolozon.jpg|thumb|The [[Cize–Bolozon viaduct]], a road–rail bridge crossing the [[Ain (river)|Ain gorge]]]]

{{See also|List of lakes in Ain, France}}

Ain is a department of geographic contrasts. In the north, the plain of [[Bresse]] is bordered by the river [[Saône]] and rises slightly towards the north-east. In the south-east, the territory of [[Dombes]] has more than a thousand ponds and lakes. In the east, the mountain chain of the southern [[Jura mountains|Jura]] overlooks the plain of Bresse. The busy transport axes to Italy and Switzerland crisscross the valleys. The [[Gex, Ain|Gex]] region is separated from the rest of the department by the last eastern mountain chain of the Jura where the highest elevation in the department, the [[Crêt de la Neige]] (1720&nbsp;m), can be found. Gex belongs geographically to the [[Lake Geneva]] basin.

The river Saône represents the western border of the department. It is fed by three smaller rivers: the [[Reyssouze (river)|Reyssouze]] (76&nbsp;km), the [[Veyle]] (68&nbsp;km) and the [[Chalaronne]] (52&nbsp;km). The river [[Rhône]] forms the department's borders in the east and the south. Its main tributaries are the Suran (50&nbsp;km) and notably the river Ain (190&nbsp;km) which is itself fed by 118 small rivers and creeks.

===Principal communes===

The most populous commune is the prefecture [[Bourg-en-Bresse]]. As of 2019, there are 8 communes with more than 10,000 inhabitants:<ref name=pop2019/>

{| class=wikitable
! Commune
! Population (2019)
|-
| [[Bourg-en-Bresse]]
| style="text-align: center;" | 41,111
|-
| [[Oyonnax]]
| style="text-align: center;" | 22,456
|-
| [[Valserhône]]
| style="text-align: center;" | 16,378
|-
| [[Ambérieu-en-Bugey]]
| style="text-align: center;" | 14,134
|-
| [[Saint-Genis-Pouilly]]
| style="text-align: center;" | 13,943
|-
| [[Gex, Ain|Gex]]
| style="text-align: center;" | 13,121
|-
| [[Miribel, Ain|Miribel]]
| style="text-align: center;" | 10,122
|-
| [[Ferney-Voltaire]]
| style="text-align: center;" | 10,026
|}

=== Transport networks ===
Ain is situated at the crossroads of a large national and international flow of commodities and is therefore an important transit region. More than 4000&nbsp;km of transport routes serve the department. In addition to a well-developed transport network of former national roads, which were transferred to the department in 2007, Ain is crisscrossed by 220&nbsp;km of highway.

For national and international flights, the international airports of [[Lyon]] ([[Lyon-Saint Exupéry Airport|Saint-Exupéry]]) and [[Geneva]] (Cointrin) are located within a rather short distance. The department of Ain also contains two waterways, the rivers Saône and Rhone, on which building materials, such as gravel, are shipped. The most important harbour is situated in [[Jassans-Riottier]] on the river Saône.

The railway network is of great importance, in particular the [[TGV]] connections Paris–Geneva (with a stop in [[Bellegarde-sur-Valserine]]) and Paris–Lyon (passing by the Saône valley). The upgraded [[Ligne du Haut-Bugey]] was opened in 2010, reducing travel time between Paris and Geneva by 20 minutes. The regional TER (train and bus) network is important mainly as concerns the connection to [[Lyon]].