More than 200 children in south west Hertfordshire have missed out on getting the secondary place of their choice as the school admission system reaches "breaking point".
Labour and Liberal Democrat county councillors have spoken of the "shocking" figures released earlier this week.
Although 95 per cent of Hertfordshire children have been allocated a place at one of their preferred secondary or upper schools, more than 630 were not.
In Watford, Three Rivers and Bushey, 222 children were placed in a school they did not want to attend.
Labour councillor Anne Joynes said: "These figures make for shocking reading where Watford pupils are concerned, 120 children in Watford haven't been allocated one of their choices."
Liberal Democrat councillor Mark Watkin said: "Through no fault of their own, these children will suffer the hardship of being separated from their school friends, and having to travel much further than they planned to a school that wasn’t in their top four preferences.
"We have been seeing the massive increase in demand for primary school places over the last few years, and here is the start of the secondary bulge.
"The pressure for additional capacity in south west Herts is near breaking point."
In total 12,080 Hertfordshire children were allocated one of their ranked schools.
Chris Hayward, executive member for enterprise, education and skills, said: "I do appreciate that some parents may be disappointed with the school they have been allocated, but would encourage them to visit the school and speak to the headteacher before dismissing the offered place. They may be pleasantly surprised by what they see."
All applicants who have not been offered their first preference school will automatically be placed on the continuing interest list for any Hertfordshire schools named higher on the application form than the school offered.