were gathered, with an average of 125K mentions per day, and a maximum of 433K mentions in a single day. The interface was public and offered real-time results.

The crawler was configured to find mentions talking about the main political parties present on the campaign and their respective candidates (only main candidates monitored, i.e., those opting to be *Lehendakari*, ‘head of the government’).

Regarding social media, Twitter was monitored. Since we are talking about monitoring an event happening on a regional scope, two main restrictions were applied: only mentions written in Basque and Spanish were crawled, because those are the two official languages in the region. The second restriction was to constrain mentions to users from the specific geographical area of the Basque Country. The task was then to discard noisy messages, that do not belong to citizens involved in the election, but were likely to be talking about it. In this case, for example the crawling process was likely to capture many mentions from other regions in Spain.

In order to solve this problem we created a census of Twitter users of the Basque Country. We developed a five step algorithm:

1.  We gathered geolocated tweets from the Basque 