Although the overall levels of support for and against independence barely changed in the Catalan election, says Robert Liñeira, there have been sizable shifts within each bloc.
Overall Picture
The Catalan Parliament elections can be summarized as follows: Important changes in party support with minor ones regarding the backing of pro-independence lists. This means that there has then been realignment within the pro-independence and pro-union blocs, but barely any changes between them. As a result, the parliamentary election brings more news than the independence plebiscite.
A quick chronicle of the election is contained in the table below, which contrasts the 2015 and 2012 outcomes. Together for Yes (JxSí), the coalition between CDC and ERC, got almost 40% of the votes. This is less than the 45.1 that Convergència i Unió (Convergence and Union/CiU) and ERC got together in 2012 and the smallest sum of the CiU and ERC share since 1980. This drop cannot be fully explained by the 2.5 of support for Unió Democràtica de Catalunya, (democratic Union of Catalonia/UDC), the former coalition partner of CDC within CiU, which stood separately in these elections and failed to get any representation.
Although 40% of the vote is not an exceptional figure for the winner of a Catalan parliamentary election, support for other parties remains so fragmented that the distance between the first- and the second-placed party is the largest ever. Also for the first time, the socialists (PSC) are not the second party in terms of popular support; Ciutadans (C’s), the party created in 2006 to fight against Catalan nationalism, is the main opposition party, which gives a first hint of the current polarisation of Catalan politics.
The support for the other parties is around the 10% mark. The socialist party (PSC) saw its share of the vote diminish at 12.8% but can take consolation in doing better than expected. The coalition between ICV and the state-wide party “We Can” (CSQEP) has not proven very successful, losing support in relative terms since previous election. (Surprisingly, none of the pre-electoral coalitions (JxS and CSQEP) appeared to get any electoral gains from their agreements). Finally, the Spanish government’s People’s Party (PP) suffered the biggest loss of the night, whereas CUP (pro-independence and radical-left) experienced - together with the Ciutadans - the biggest win and becomes the key actor in the formation of the new government.
Turnout
Turnout was the most remarkable aspect of the whole election. It shows that independence mobilises votes like nothing else. By way of context, referendums in Scotland and Quebec referendums hit unprecedented levels of turnout, and this election – where the independence debate has been at the forefront of the campaigns - has achieved a record turnout for Catalan parliamentary elections - 77.4%. This is almost 10 percentage points higher than the previous record established in the election of 2012. Sunday’s level turnout has only been surpassed in Catalonia by the founding democratic general elections of 1977, and the electoral landslide of 1982 - which took the socialists to power for the first time.
In contrast to the expectations of some, high-turnout did not affect balance between pro-independence and pro-union candidacies. In 2012, the pro-independence parties (CiU+ERC+CUP) received 48.6% of the valid votes on a 67.85 turnout. Now, support for pro-independence parties is 47.9% (JxSí+CUP). In fact, the mobilisation has been almost as prominent in pro-independence municipalities as in pro-union ones, which suggests that this election mobilized both sides in a similar way.
Change in the vote
The increased turnout meant that there were 450,000 more votes in ballot boxes than in 2012. This increase in the available votes meant that almost no party lost votes in absolute terms. The sole exception to this rule is the PP, which lost 26% of its support (more than 120,000 votes) and saw its vote share drop from 13.2% to 8.5% (see figure below). In contrast, the Ciutadans and CUP experienced the biggest gains. Both parties managed to multiply their number of votes by 2.67, more than 450,000 extra votes for the Ciutadans and 210,000 for the CUP. As for JxSí, the PSC and CSQEP, the number of votes they received barely changed from the previous election, although the surge in turnout means that they lost support in relative terms.
It is difficult to assess which vote flows best explain these changes with the data currently available and without going into more detail than a post of this length would allow; the net change in a party support always hides different sources of gains and losses. However, we can use the change in party support across the 947 Catalan municipalities to infer some flows. Some of these patterns are sufficiently clear as to be worth underlining.
The figure below contains three scatterplots. Every dot represent one of the 947 Catalan municipalities, and each of the scatter axes shows the change in the share of the vote for different parties. The scatter on the right contrasts the evolution of the support of the Ciutadans and the PP, whereas the other two contrast the evolution of support for CUP, in contrast to the support for JxSí CSQEP respectively.
As seen in the figure on the right, most of the dots are in the first quadrant, specifically, the ones that relates losses for the PP and gains for the Ciutadans. The shape of the dots also shows that it is precisely in those municipalities where the Ciutadans experience the biggest gains where the PP suffers the biggest losses. This suggests important transfers of votes from PP to Ciutadans. The Ciutadans have also been successful in getting new voters, experiencing its biggest gains in those areas where turnout has increased the most.
The other two figures show CUP gains are not as neat as the one for Ciutadans, but some patterns emerge. According to our data they managed to get votes from the municipalities where CiU and ERC were strong in 2012 (especially in those municipalities where ERC was particularly strong, suggesting that it is from this party that they experience their largest gains) but also from CSQEP (which stood as ICV in 2012). The transfer from ICV to CUP is the most significant flow between pro-independence and pro-union parties.

Conclusion
In summary, support for pro-independence parties is not far away from the vote share they received in 2012. The main difference is that this time they ran on a clearer pro-independence platform than the one on which they campaigned three years ago. However, there has been some realignment within each side; Ciutadans is more prominent on the pro-union side, and CUP is now stronger within the pro-independence ranks. In short, the question of independence polarises the Catalan Parliament more than ever before.
It is also evident that, although pro-independence parties dominate Catalan politics, they lack the strength to go for independence. In vote after vote, the news is the same. With the next bulletin due from the Spanish general election in December this year, this raises the question of whether the time has come for the Spanish and Catalan governments to sit down and agree a way to channel the demands of almost half of the Catalan electorate.