Information compiled from the Red Book
by Lady Elwing please do not put it on your site.

Boromir set out from Minas Tirith during the Summer Days [July 4 Shire], 2018 TA. We know that he stayed at the foot of the Ered Nimrais until reaching the Gap of Rohan. Upon scrutiny this route would take him on the "Great West Road" of Gondor. Assuming he used it, Boromir would have passed along the Beacon Hills and towers of Mardol, Erelds, Minrimmon, Calenhad, and Halifirien. At that point he would have passed through Firien Wood and crossed a south tributary of the Entwash, Mering Stream. From there it was about sixty miles over open plains to Edoras. It is unknown whether he stopped there, but it would have been a good place to acquire new provisions and rest his horse. This part of the journey would have been 300 miles and have taken him about 23 days to complete. he would have reached Edoras around July 23[28 Shire] 3018 TA.

The second leg of his journey would have taken him past Isengard through the Gap of Rohan. After leaving Edoras, Boromir would have had to cross the rivers Isen and Adorn. At that point he would have continued on the Old South Road of Gondor until he reached the ancient town of Tharbad. This would have taken him 413 miles and about 32 days (August 25[30 Shire] ).

Tharbad was built in the early TA by the Dunedain when Arnor and Gondor were still strongly linked. It later fell in the wars with Angmar and was deserted. In the ruins of the town was the crossing of the Greyflood, a major river in that area. Boromir unfortunately came into great peril while fording it and lost his horse in the swirling waters. Fortunately he was a skilled swimmer ( he had escaped Osgiliath by that method). At this point Boromir could have A) Followed the Greenway or B) Followed the River Hoarwell. Since there was no evidence of Boromir arriving in Bree, it is safe to assume he chose the river route.

During this part of the journey he would have been going vaguely parallel with the Misty Mountains. After a time he would reach the Loudwater [Bruinen], one of the rivers of Imladris - only he probably did not know that. At this point he was bereft of his horse and all he could do was ask around to see if anyone knew where Imladris was. He could have wandered a good deal around the area before finally finding the way to Imladris itself. This part of the journey took him about 415+ miles and 55 days until he reached Rivendell on October 22[25 Shire] 3018 TA in "the grey light of dawn" just in time for the Council of Elrond.

In conclusion, his journey shows the resources and skill of Boromir to go so far in a strange country to find a place that nobody knew existed. He should be held in high esteem even for the feat of his journey.

"In this evil hour I have come on an errand over many
dangerous leagues to Elrond: a hundred and ten days
I have journeyed all alone. But I do not seek allies in war...
I come to ask for counsel and the unravelling of hard words."

Note: All dates converted to Steward's Reckoning