The route impressed the agents as a natural and desirable one. Sorrels, who had participated in Presidential protection assignments in Dallas since a visit by President Franklin D. Roosevelt in 1936,[C2-39] testified that the traditional parade route in Dallas was along Main Street, since the tall buildings along the street gave more people an opportunity to participate.[C2-40] The route chosen from the airport to Main Street was the normal one, except where Harwood Street was selected as the means of access to Main Street in preference to a short stretch of the Central Expressway, which presented a minor safety hazard and could not accommodate spectators as conveniently as Harwood Street.[C2-41] According to Lawson, the chosen route seemed to be the best. It afforded us wide streets most of the way, because of the buses that were in the motorcade. It afforded us a chance to have alternative routes if something happened on the motorcade route. It was the type of suburban area a good part of the way where the crowds would be able to be controlled for a great distance, and we figured that the largest crowds would be downtown, which they were, and that the wide streets that we would use downtown would be of sufficient width to keep the public out of our way.[C2-42] Elm Street, parallel to Main Street and one block north, was not used for the main portion of the downtown part of the motorcade because Main Street offered better vantage points for spectators. To reach the Trade Mart from Main Street the agents decided to use the Stemmons Freeway (Route No. 77), the most direct route. The only practical way for westbound traffic on Main Street to reach the northbound lanes of the Stemmons Freeway is via Elm Street, which Route No. 77 traffic is instructed to follow in this part of the city. (See Commission Exhibit No. 2113, p. 34.) Elm Street was to be reached from Main by turning right at Houston, going one block north and then turning left onto Elm. On this last portion of the journey, only 5 minutes from the Trade Mart, the President’s motorcade would pass the Texas School Book Depository Building on the northwest corner of Houston and Elm Streets. The building overlooks Dealey Plaza, an attractively landscaped triangle of 3 acres. (See Commission Exhibit No. 876, p. 33.) From Houston Street, which forms the base of the triangle, three streets--Commerce, Main, and Elm--trisect the plaza, converging at the apex of the triangle to form a triple underpass beneath a multiple railroad bridge almost 500 feet from Houston Street.[C2-43] Elm Street, the northernmost of the three, after intersecting Houston curves in a southwesterly arc through the underpass and leads into an access road, which branches off to the right and is used by traffic going to the Stemmons Freeway and the Dallas-Fort Worth Turnpike. (See Commission Exhibits Nos. 2113-2116, pp. 34-37.) [Illustration: COMMISSION EXHIBIT NO. 876