[2][4] The first segment of the new highway, from US 1 to what was then MD 216 near Brock Bridge Road in what is now Maryland City, was started in 1943 and completed in 1944.

[3] The remainder of MD 602, from near Brock Bridge Road to the entrance to Fort Meade near the Little Patuxent River, was completed by 1946.

[5] Maryland Route 619 was the designation for Locust Street and Quaker Hill Road from MD 75 in Union Bridge southeast toward McKinstry's Mill in western Carroll County.

[34] Maryland Route 628 was the designation for Rice Road and part of Resley Road from what is now Old Route 40 east of Sideling Hill north and east to the Pennsylvania state line in far western Washington County.

[5] That highway was part of the original route of MD 313, which was designated and paved through southern Caroline County by 1927.

[5] Maryland Route 639 was the designation for a short portion of White Church Steyer Road east from MD 560 near Gorman in southern Garrett County.

[15] Maryland Route 640 was the designation for Thurston Road from Bennett Creek north to MD 80 near Urbana in southern Frederick County.

[5] Maryland Route 647 was the temporary designation for Guilford Road for a short distance on either side of its Baltimore & Ohio Railroad crossing at the Anne Arundel–Howard line at Annapolis Junction.

[4][32] Maryland Route 651 was the designation for St. Clair Bridge Road south from MD 165 near Pylesville in northern Harford County.

[9] Maryland Route 652 was the designation for Orleans Road from US 40 (now US 40 Scenic) north to the Pennsylvania state line near Bellegrove in eastern Allegany County.

[4][28] Maryland Route 653 was the designation for the extension of 16th Street from the District of Columbia boundary north to MD 410 in Silver Spring in southeastern Montgomery County.

[MD 657 5] Coincidentally, in March 2010, a 50-foot-wide (15 m) section of the state highway was damaged by a torrent of water released from an abandoned mine following several days of rainfall, requiring an emergency repair project that reduced the roadway's width at the site from 15 feet (4.6 m) to 13.5 feet (4.1 m).

[MD 657 8] Maryland Route 661 was the designation for Quaker Neck Landing Road, which ran 2.22 miles (3.57 km) from MD 289 near Pomona to a dead end at the Chester River in central Kent County.

[MD 661 1] Maryland Route 662 was the designation for Turners Creek Road, which ran 3.13 miles (5.04 km) from the railroad crossing in Kennedyville north to the end of state maintenance near Turners Creek, a tributary of the Sassafras River, in northern Kent County.

[MD 662 6] Maryland Route 663 was the designation for Camden Avenue from US 13 (now US 13 Business) south of Fruitland north to US 50 (Main Street) in Salisbury in central Wicomico County.

[40][41] This segment, the portion of Camden Avenue in the city, and Allen Road south of Fruitland became part of US 13 in 1927.

[5] Maryland Route 664 was the designation for Wilkins Lane, which ran 1.65 miles (2.66 km) from MD 289 near Chestertown to a dead end near the Chester River in central Kent County.

[24] Maryland Route 669 was the designation for Benevola Church Road west from MD 66 near Boonsboro in eastern Washington County.

[45] The highway's western end was rolled back to MD 170 (now Piney Orchard Parkway) in 1985.

[47] Maryland Route 678 was the designation for Deer Park Road northwest from MD 91 near Finksburg.

[5] Maryland Route 680 was the designation for two disjoint segments of Gillis Falls Road near Woodbine in southwestern Carroll County.

[32] Maryland Route 682 was the designation for Church Street from MD 86 in Lineboro in northeastern Carroll County north to the Pennsylvania state line.

[5] Maryland Route 683 was the designation for Poole Road southeast from US 140 (now Main Street) in Westminster in central Carroll County.

[5] Maryland Route 685 was the designation for a pair of roads on the south side of the Bohemia River at Hack Point in southern Cecil County.

[MD 685 3] Both sections of the highway were returned to county maintenance through a December 27, 1979, road transfer agreement.

[49] Maryland Route 687 was the designation for Gillis Road east from MD 27 near Taylorsville in southwestern Carroll County.

[24] Maryland Route 690 was the designation for Half Mile Turn and Sylmar Road, which together ran 1.46 miles (2.35 km) from MD 273 east of Rising Sun north to the Pennsylvania state line in northern Cecil County.

[51] Maryland Route 693 was the designation for what is now Renner Road between its intersections with MD 5 near Waldorf in northern Charles County.

[5] Maryland Route 696 was the designation for Perryhawkin Road east from MD 388 near Princess Anne in northern Somerset County.

[MD 697 1] Maryland Route 698 was the designation for Mill Street, which ran 0.11 miles (0.18 km) from High Street west to the east side of the railroad (now the Chestertown Rail Trail) in the town of Chestertown in central Kent County.