Local government workers across England, Northern Ireland and Wales struck for two days alongside civil servants against sub-inflation pay rises.
More than 500,000 workers were on strike on July 16 and 17, bringing disruption to schools, town halls, refuse collections and libraries throughout England, Wales and Northern Ireland.
"This has been a fantastic response from our members," said UNISON general secretary Dave Prentis. "Local government workers have shown their anger and resentment towards this pay offer.
"The employers must heed the voice of their own workforce and get back round the negotiating table to settle this dispute."
Reports from round the regions show solid support in all major towns and cities. As well as the closure of 11,000 schools, examples of the action have included:
Merseyside waste disposal: shut down;
South Tyneside libraries and leisure centres: closed;
Kirkless refuse collections: cancelled;
Derry and Haverfordwest airports: closed;
Wolverhampton libraries: closed;
Wakefield refuse collections: cancelled;
Coventry street cleaning: cancelled;
South Somerset benefits office: closed.
"These members have not taken this action lightly," added Mr Prentis. "But for the fourth year running they are offered a take it or leave it pay cut. They are saying 'enough is enough'.
Also on strike were local government workers in Unite and, in Northern Ireland, Nipsa, as well as driving instructors in the PCS.