US 13 initial routing 1926 Official

US 13 truncated to Cape Charles 1926 Official

US 13 ending at end of Mason 1935 Northampton County

US 13 extended around on Bayview Ave 1936 Northampton County

In July 1943 (AASHO), US 13 was continued across the Cape Charles ferry to Little Creek, then replaced VA 13 down Diamond Springs Road, Waterworks Rd, Princess Anne Rd, and Military Hwy around the Tidewater area to end at US 58 (now VA 191) Bowers Hill. Note that Virginia had been trying to get US 13 extended across the bay since 1926!
In Sept 1945, the Interregional System of Highways was distributed to the CTB. They approved all the routes therein for Virginia (except wanted to change US 211 as a corridor to VA 55), plus added 2 more corridors. One was US 13 from Cape Charles to Maryland, "provided the Public Roads approves the addition within Delaware and Maryland." The next mention of the Interregional System of Highways occurs in the April 1958 CTB, which summarizes what happened in 1945 and notes that the Bureau of Public Roads only accepted one of the 2 additional corridors, US 301 from NC to Petersburg.
Sometime in 1950 (per April 1951 CTB), US 13 was rerouted from Cape Charles to the Kiptopeke Ferry location. Some of this was a replacement of VA 186. The road to Cape Charles became US 13 ALT (now VA 184). See scan under US 13 ALT entry.
In Oct 1950 (CTB), US 13 was removed from Waterworks Rd and Princess Anne Rd, leaving behind VA 165Y (east of I-64 is physically gone) and VA 165. US 13 was instead placed on Northampton Blvd in this area.
In Oct 1951 (AASHO), US 13 was extended along US 58-460 to Magnolia, VA 337 into central Suffolk, then after a brief VA 32 duplex south, replaced VA 37 through Whaleyville and into North Carolina.

VA 13 in Tidewater area. 1941-42 Official

US 13 extended to Bowers Hill 1944 Official

US 13 extended through Suffolk to NC 1952 Official

In Oct 1957 (CTB), US 13 was placed on Hall Ave between Saratoga Ave and Washington St in Suffolk, leaving behind VA 337.
In Feb 1958 (AASHO), South Carolina tried to have US 13 from Norfolk to Maryland renumbered as part of a huge extension of US 5. It is unclear what was supposed to happen to US 13 from Norfolk to Goldsboro NC. No other state joined in, so this, of course, went nowhere.
In May 1960, the CTB requested an interstate corridor on the Eastern Shore. it is unclear what happened to this other than it didn't happen.
In Feb 1964 (CTB), US 13 was moved from Diamond Springs Rd to Northampton Blvd and over the new Chesapeake Bay Bridge-Tunnel as a route swap with VA 166. In Northampton County, US 13 was removed from Kiptopeke, leaving behind SR 704 which is still 4-lane concrete.

US 13 using Waterworks Rd 1944 Official

US 13 using Northampton and Diamond Springs 1956 Official

US 13 using Northampton only 1965 Official

In Oct 1966 (CTB), US 13 received bypasses of Cheriton/Bayview, Eastville, Exmore, and Onley/Tasley/Accomac C.H. All old routings became US 13 Business segments.

US 13 through every town on the Eastern Shore 1966 Official

US 13 bypasses Cheriton/Bayview, Eastville, Exmore, and Onley/Tasley/Accomac C.H. 1967 Official

In Aug 1970 (CTB), US 13 was placed on I-64 from Bowers Hill to Northampton Blvd, leaving behind US 13 Business.
In June 1974 (CTB), US 13 was removed from Hall Ave and VA 337 and instead began using today's US 13 Business through Suffolk. Oddly, officials from 1975-80 and county maps through at least 1981 show US 13 on its old routing, when they never showed it when it was actually happening.
In June 1980 (AASHTO), US 13 was returned to Military Hwy and Northampton Blvd, replacing US 13 Business.

US 13 Bus in Chesapeake 1971 Official

US 13 returned to Military Hwy 1981 Official

On March 19, 2003, US 13 was rerouted to go around the west side of Suffolk as new constructed freeway, although posting of the original Suffolk Bypass with US 13 shields took a couple months longer.

US 13 through central Suffolk 1957 Nanesmond County

US 13 using Hall Ave and Washington Ave 1958 Nanesmond County

US 13 bypasses Suffolk entirely 2004 Official

In 2006, the General Assembly directed DOT to study the idea of an I-99 to run up the Eastern Shore. Go to the I-99 page for details.
Improvements:  Upon designation in 1926, US 13 was paved from Cape Charles to Sunny Side; Keller to Rue; Oak Hall to Maryland.
In 1928, US 13 was paved from Rue to oak Hall
In 1929, the rest of US 13 was paved
The First segment of US 13 to be multilaned was when it was added to Military Hwy around 1943.
In 1949, US 13 was multilaned from Accomac C.H. to VA 176 and from VA 175 to Maryland.
In 1951, US 13 was multilaned on its Northampton Blvd and diamond Springs Rd routings; also from Temperanceville to Oak Hall.
In 1952, US 13 was multilaned when it was added to US 58-460 from Bowers Hill to Magnolia.
In 1953, US 13 was multilaned from VA 176 to Mappsville.
In 1954, US 13 was multilaned from Mappsville to Temperanceville; erroneously shown as widened from onley to Tasley
In 1958, US 13 was multilaned from SR 683 to the Kiptopeke Ferry Landing
In 1959, US 13 was multilaned from SR 683 to SR 684.
In 1964, US 13 was multialned from old US 13 (now SR 704) south to the Chesapeake Bay Bridge-Tunnel; also US 13 was multilaned when moved to its all-Northampton Blvd routing.
The 1965 and 1966 Officials show US 13 widened from SR 684 to north of Eastville, although no bypasses are shown. This may be a premature showing on the map or US 13 was widened between bypass segments.
In 1967, US 13 was multilaned on its bypasses of Cheriton, Eastville, Exmore and Onley/Tasley/Accomac
In 1969, US 13 was multilaned from Eastville to Exmore; Exmore to Onley
In 1974, US 13 was 4-laned from Magnolia to Suffolk when it was removed from VA 337 and Hall Avenue.
In 1976, US 13 was widened from Suffolk south to the VA 32 split.
In 1999, US 13 was multilaned on the bridge segments of the Chesapeake bay Bridge-Tunnel.
In 2003, US 13 was multilaned around Suffolk when rerouted onto its Suffolk Bypass (full freeway).
US 13 is 6-lanes from US 60 to VA 166; I-64 to Military Hwy; Indian River Rd to Auburn Dr; Allison Dr to VA 168; Bowers Hill to Suffolk Bypass
US 13 is 8-lanes from Diamond Springs Rd to I-64; Lowery Rd to US 58; I-264 to Indian River Rd.
US 13 is 10-lanes from US 58 to I-264.
The remaining 2-lane segments are: NC to VA 32; Chesapeake Bay Tunnels
Posted:  Fully posted; mainline US 13 cutouts on the Eastern Shore gradually disappeared during the 2000s, the last known cutout at SR 642 below Cheriton still remained in April 2007 but was gone by 2013. The last Tidewater area cutout was at the former VA 32 ALT intersection in Suffolk which was still there in 1994, but long gone now.
A series of "TO US 13" trailblazers exists on westbound VA 166 in Norfolk, including one just west of the US 13/VA 165/VA 166 intersection.
Multiplexes:  VA 32 (4.44 mi)
US 58, VA 32 (1.88 mi)
US 58, US 460, VA 32 (0.93 mi)
US 58, US 460 (10.04 mi)
US 460, VA 191 (0.18 mi)
US 460 (7.47 mi)
VA 165, VA 166 (0.10 mi)
VA 166 (1.93 mi)
VA 180 (0.46 mi)
Legislative names:  Ocean Highway, US 17 to Maryland Line except Business segments(since 3/23/46); Charles M. Lankford Jr memorial Highway, Northampton/Accomack Counties (since 1978)
Dr. Martin Luther King, Jr Memorial Bridge, Lake Kilby (designation 12/18/01);
Other names:  Whaleyville Blvd/Carolina Rd (S Suffolk); Military hwy (E Suffolk/Chesapeake/Norfolk); Northampton Blvd (Norfolk/Va Beach).
Scenic Byway:  None
Comments: US 13 now (since mid-2004) has mile markers from the north end of the Chesapeake Bay Bridge-Tunnel (MM 70) to the Maryland State Line (MM 138).
Westbound along VA 166/Princess Anne Rd has TO US 13 trailblazers. This may not seem like much, except that it's moving away from US 13 at the Princess Anne Rd/Northampton Blvd/Military Hwy intersection (where US 13 meets with VA 166). Turns out they direct you to turn left on Azalea Garden Rd to reach US 58 where one can jog east back to US 13. I guess people didn't notice Military Hwy when coming down Northampton Blvd.
L. Corsaro and E. Smith have a US 13 expressway site
Froggie has a photo journey of the Suffolk Bypass of US 13 - here.
From Dave:

The main drag of the Delmarva Peninsula, which I became familiar with as a child on my family's biannual trips to my great aunt's home in Jarvisburg, NC. Highlights include: one of my favorite town names - Mappsville, Owl Restaurant in Accomac, and, of course, the famous Bridge-Tunnel.