The M25 accounted for five of the UK's top ten worst traffic jams in July, according to data analysed by the TomTom HD Traffic Centre.
The longest tailback was on Friday, July 29, at 5.45pm, from junction 19 near Watford to junction 5 at Sevenoaks, with traffic queuing for 49 miles.
The worst non-motorway tailback in July was on the A64 from Eastfield towards the A1237 interchange at York, with a queue of 30 miles on Sunday July 3 at 8.21pm. This incident came second in the overall list of blackspots.
The section of the M25 from junction 8 at Reigate to junction 16 (the M40 interchange) appears twice in the list - with delays of 27.5 miles and 26 miles on the Friday afternoons of July 8 and 22.
The A1 from Eyemouth to South Charlton, and the A49 from Ludlow to Shrewsbury also appeared in the top ten.
The worst traffic peak of the month was at 3.58pm on Friday 8 July , when there were 1027 miles of jams across the country as a whole. The average jam length at any one time across the whole country in July was 148 miles.