A closer look at US 29's original routing:
Old US 29 at the NC Line at Danville; US 29 Bus; VA 41; US 29 Business; SR 1031 Suburban Dr and SR 720 Blairs Cir in Blairs; US 29 to Chatham except Old Taylor Rd/abandoned alignment south of SR 718 Dry Fork Rd; US 29 through Tightsqueeze.
US 29 used US 29 Business through Chatham, then SR 1429; US 29; US 29 Business through Gretna; US 29, SR 988 to US 29 Business through Alta Vista; SR 712 Riverbend Rd, US 29; SR 912; US 29; SR 754 Anstey Rd, SR 738 Greenhouse Rd; US 29; US 29 Bus; VA 163 through Lynchburg to Madison Heights.
US 29 followed US 29 Bus through Amherst except SR 671 in Monroe and Faulconerville Dr at Faulconerville. North of Amherst, US 29 followed VA 151 then VA 151Y, then VA 56 east back to modern US 29 and 29 Business into Lovingston.
From Lovingston, US 29 used SR 770 Cannery Loop but otherwise modern 29 to Woods Mill. US 29 followed VA 6 west then VA 6Y east back to current US 29 which it followed pretty closely to Covesville, using Covesville Ln through the community. Then US 29 followed its current routing to about I-64, then used Teel Ln and on the other side of I-64 picked up SR 702 which becomes US 29 Business. US 29 followed that to Emmet St, then turned right and followed Emmet St to Main St. US 29 went east on Main then north on Rugby out to SR 743 which it followed to US 33.
US 29 used US 33 to SR 645 north back to current US 29 which it followed to Culpeper except used SR 631 Kirtley Rd; Mays Ln; SR 717/643 loop near Reva; US 29 Business into Culpeper.
Adjustments:By 1932, US 29 was placed on current VA 293 north of VA 41 and modern US 29 Business through Blairs.
In July 1933, VA 14, VA 18, and VA 28 were dropped from US 29.
In Oct 1934 (CTB), US 29 was removed from SR 717/643 loop west of Culpeper.
In 1934, US 29 was extended north with US 15 to Warreton then east with US 211 to Washington DC.
Also in 1934, US 29 was rerouted onto current US 29 Business and US 29 from Main St Charlottesville north past Ruckersville, leaving behind SRs 743/644 (now just 743), VA 4 (now US 33), and SR 645.

U.S. 29, original Ruckersville approach 1932 Official

U.S. 29, new Ruckersville approach 1934 Official

About 1935, US 29 was placed on today's SR 762 between Inlet and Brandy Station.

US 15-29 south of RR 1932 Culpeper County

US 15-29 north of RR 1936 Culpeper County

I believe US 29 was removed from SR 770 north of Lovingston in the mid-1930s.
About 1937, US 29 was given its original bypass (with US 15) around Warrenton to the west, leaving behind US 15 ALT.
It appears that US 29 was put on its modern routings at Leon and Brightwood in March 1938 (CTB), leaving behind SR 647/607 loop; SR 607/678 loop north of Brightwood; SR 631
In Oct 1947 (CTB), US 29 was put on newly constructed routing from Amherst to Colleen, leaving behind VA 151 and VA 158. The new route may have used a tiny bit of VA 150.

U.S. 29, original Amherst to Lovingston approach 1947 Official

U.S. 29, new Amherst to Lovingston approach 1948 Official

In Dec 1947 (CTB), US 29-211 was removed from the SR 674/693 loop at New Baltimore.
In 1948, US 29 was placed on today's US 29 Business north out of Culpeper, leaving behind SR 727 (Piedmont St/Clay St/Old Brandy Rd)

US 29 east out of downtown Culpeper south of VA 3 1936 culpeper County

US 29 north past US 522 (old VA 3) out of downtown Culpeper 1958 culpeper County

About 1952, US 29 was placed on its current North Carolina crossing, leaving behind SR 657 (now unnumbered) into North Carolina.
In Oct 1953 (CTB), US 29 was removed from SR 712 north of Altavista.
By 1958 (likely years earler), US 29 was removed from SRs 738 and 754 north of VA 24.
In Aug 1955 (CTB), US 29 was rerouted in Lynchburg to continue along Fort Ave, then south on Campbell Ave to the new completed portion of the Lynchburg Expressway, then using the new road across the James River to meet back up with the original route in Madison Heights. The old route through downtown Lynchburg became US 29 ALT (now VA 163).
In Sept 1959 (CTB), US 29 was placed on more completed Lynchburg Expressway leaving behind more US 29 ALT (now VA 163).

US 29 original Lynchburg route 1947 Official

US 29 rerouted in Lynchburg 1957 Official

US 29 added to more Expressway 1961 Official

In Jan 1960 (CTB), US 15-29 was removed from SRs 685/676 between Brandy Station and Elkwood.
In 1960-61, US 29-211 and VA 309 swapped alignments to today's configuration. US 29-211 had used Lee Hwy all the way through here.

US 29-211 on Lee Hwy all the way 1949 Official

US 29-211 swap segments with VA 309 1961 Official

In Jan 1962 (CTB), US 29 was given its bypass of Madison, leaving behind US 29 Business and a part of VA 231.
In May 1964 (CTB), the Executive Secretary of Prince William County requested that US 29 be rerouted along VA 28 from Remington to Centreville via Manassas so that Manassas can have a US Route.
About 1965, US 29 was given its bypass of Chatham, leaving behind US 29 Business and part of SR 1429.

US 29 Bypasses Madison 1963 Official

US 29 Bypasses Chatham 1963 Official

In Oct 1966 (CTB), US 29 was given its bypass of Charlottesville utilizing new construction plus existing US 250 bypass. This left behind Teel Ln, SR 702, and US 29 Business.

U.S. 29 original Charlottesville routing 1932 Official

U.S. 29, new Charlottesville routing 1941-42 Official

US 29 Bypasses Charlottesville 1970 Official

Also about 1966, US 29 was rerouted at Woods Mill to its current routing leaving behind VA 6Y and VA 6 (routes have since swapped).
In Sept 1967 (CTB), US 29 was removed from SR 779 in the Red Hill area.
In Feb 1969 (CTB), US 29 was given its bypass of Lovingston, leaving behind US 29 Business and a part of VA 56.
In Nov 1969 (CTB), US 29 was given its bypass of Amherst, leaving behind US 29 Business.

US 29 Bypasses Lovingston 1971 Official

US 29 Bypasses Amherst 1971 Official

In Dec 1970 (CTB), US 29 was assigned to what had been the US 29 ALT bypass around the west side of Danville. The route through Danville became US 29 Business (now VA 293).
In April 1971 (CTB), US 29 was placed on its Brightwood Bypass leaving behind SR 607/730.
About 1971, US 29 was rerouted in Danville off of Piney Forest Rd south of Parker Rd onto new routing across the Dan River, then west on Riverside Dr. The old route had been a US 58 duplex west to Park Ave south across the Dan River.
In Aug 1972 (CTB), US 29 was removed from SR 671 in the Five Forks area north of Madison Heights.
In 1973, US 29 was given its Culpeper Bypass, leving behind US 15-29 Business.
In May 1974 (CTB), US 29 was removed from SR 988 in Motley. This is likely when US 29 received its bypass of Hurt and Altavista, leaving behind US 29 Business.
Around 1975, US 15-29 was given its modern routing from Inlet past Brandy Station to Remington, leaving behind OSR 15-29 (now SR 762) and also SRs 685/755.
Also around 1975, US 29 received its bypass of Gretna, leaving behind US 29 Business.
In Sept 1975 (CTB), US 29 was given its bypass of Remington, leaving behind US 15-29 Business.

US 29 Bypasses Culpeper and Remington 1978 Official

US 29 Bypasses Gretna and Hurt/Altavista 1975 Official

In June 1978 (CTB), US 29 was removed from Faulconerville Rd.
In Dec 1978 (CTB), US 29 was removed from SRs 838 and 841 through Covesville.
In July 1980 (CTB), US 211 was removed from US 29.
In 1986, US 29 was placed on the new freeway bypass of Warrenton around to the east. This left behind US 29 Business.

US 29 in Warrenton 1936-86 1941-42 Official

US 29 in Warrenton since 1986 2002 Official

In 1998, US 29 was placed on its bypass around the east and south of Danville using new construction north of US 58 and replacing VA 265 south of US 58.

US 29 Danville routing 1931-70 1941-42 Official

US 29 Danville routing 1971-98 1971 Official

US 29 Danville routing since 1998 2006 Official

In Oct 2005, US 29 was placed on newly constructed freeway from the south end of the Amherst Bypass to US 460 east of Falwell Airport. US 29 now follows US 460 west to meet back up with US 29 near Lynchburg Airport. The freeway from US 460 to VA 210 opened in Dec 2004. The old route past Sweet Briar College and through Madison Heights became part of a very long US 29 Business.
Improvements:  Upon designation in 1931, US 29 was fully paved everywhere except from Ruckersville to the Rapidan River, which was corrected when US 29 moved to modern routing there in 1934.
The first multilaning of US 29 occurred between 1941-47, from Fairfax Circle west to the current 2-lane segment of US 29 approaching Manassas Battlefield.
In 1954, US 29 was multilaned from about VA 215 to US 15 NB.
In 1955, US 29 was multilaned from Charlottesville north a couple miles.
In 1956, the 1955 widening was extended to the S. Rivanna River; the 1954 widening was extended west to the east end of the Warrenton Bypass; also from about VA 55 to the east edge of Manassas Battlefield
In 1957, US 29 was multilaned from US 15 to VA 55.
In 1958, US 29 was multilaned from S. Rivanna River to SR 649.
In 1960 or 1961, US 29 was 4-laned from the Bannister River through Chatham; Whittles through Gretna; Lynchburg Expwy south of the James River; VA 120 to VA 124; also incorrectly shown to be 4-laned undivided through Manassas Battlefield (until 1975 issue on insets; 1981 on the main maps).
In 1962, US 29 was 4-laned from VA 120 west to VA 237 Falls Church.
In 1963, US 29 was multilaned from NC line to today's VA 293; the 1960 widening through Chatham was redrawn to be from SR 718 to the Bannister River and not through Chatham; the 1960 widening from Whittles to Gretna was redrawn to be Whittles south to what is now the north end of the Chatham BYpass.
In 1965, US 29 was widended on the new Chatham Bypass; Lynchburg Airport to Lynchburg Expwy; SR 649 north to Greene County; west to the WCL of Falls Church.
In 1966, US 29 was multilaned from James River to VA 130; Myndus to Woods Mill; Culpeper south a mile; Opal to the original Warrenton Bypass
In 1967, US 29 was multilaned from VA 24 to Lynchburg Airport; north of Lovingston to Myndus; north of SR 692 to US 250 with a small gap south of today's I-64.
In 1968, US 29 was multilaned from VA 24 south several miles; Albemarle/Greene Line to south end of Madison Bypass; from VA 28 to Opal.
In 1969, US 29 was multilaned from the north end of today's VA 293 to SR 718; VA 130 to Monroe; Lovingston Bypass; north of Brightwood to Culpeper
In 1970, US 29 was multilaned on its new US 58 duplex; the 1868 widening was extended south to SR 712.
In 1971, US 29 was multilaned from VA 86 to Parker Rd; Monroe to north of VA 151; Madison Bypass north to past Brightwood
In 1972, the Monroe widening was extended to Nelson County line; Colleen to Lovingston; Covesville to the north of SR 692.
In 1973, US 29 was multilaned from Colleen south to Amherst line; on its new Culpeper Bypass
In 1974, US 29 was multilaned from SR 712 south on the bypass of Altavista, Hurt, and Motley.
In 1975, US 29 was multilaned on the Gretna bypass; the small gap south of I-64; US 250 duplex; from the Culpeper Bypass to VA 28; Fairfax Circle to Falls Church.
In 1977, US 29 was multilaned from VA 6 to Covesville
In 1978, US 29 was multilaned from Gretna bypass to Motley.
In 1979, US 29 was multilaned on most of its VA 6 duplex
In 1980, US 29 was multilaned on the rest of the VA 6 duplex
In 1983 or 1984, US 29 was multilaned from Parker Rd to the north end of today's VA 293.
In 1998, US 29 was multilaned on its new Danville Bypass routing from the NC Line to US 58-360.
In 2005, US 29 was multilaned from US 58 north to US 29 Bus Blairs; the new Madison Heights Bypass plus US 460 duplex were multilaned upon opening.
The only 2-lane segment of US 29 remaining is within the Manassas Battlefield Park.
US 29 is a full freeway on the bypasses of Danville, Chatham, Gretna, Hurt-Altavista, Lynchburg-Madison Heights-Amherst, Charlottesville, and Warrenton. The Culpeper Bypass is full freeway except around the SR 666 at-grade intersection.
US 29 is 6-lanes from the Charlottesville Bypass to SR 743; 8-lanes from SR 743 to SR 643 at the S. Rivanna River; 6-lanes from I-66 to VA 28 in the Centreville area; 6-lanes from Summit Dr to Legato Rd west of Fairfax City; 6-lanes from Eaton Pl to Fairfax Circle; 6-lanes from I-66 (exit 72) to the DC Line
Posted:  Fully posted;
The only mainline US 29 cutouts thought to be remaining are in Falls Church. The Madison Bypass cutout set was replaced in 2012.
A VA 29 shield existed briefly on US 60 WB at the Amherst Bypass but has been corrected. A bonus error - in 2003 I spotted FL 29 shields in Pensacola. There is an erroneous Seminole Trail sign SB near VA 215 which is north of its legislative end in Warrenton.
Multiplexes:  US 58 (6.96 mi)
US 460 (incl. triplex) (5.95 mi)
US 460, US 501 (1.91 mi)
VA 56 (4.28 mi)
VA 6 (3.94 mi)
US 250 (2.33 mi)
VA 230 (0.52 mi)
VA 231 (1.34 mi)
US 15 (incl triplex) (32.16 mi)
US 15, US 17 (7.14 mi)
US 50 (2.62 mi)
VA 237 (6.70 mi)
VA 309 (0.05 mi)
Legislative names:  29th Infantry Division Memorial Hwy from NC Line to DC Line (since 4-7-93); Seminole Trail from NC Line to Warrenton except for bypass routes (2-16-28 designation predates US 29); Danville Expressway from NC Line to VA 41 (since 1-28-93); Dan Daniel Highway from VA 41 to US 29 Bus Blairs (since 1-28-93); Robert C. Vaden Highway on Gretna Bypass (since 3-20-91); Lee Highway from Warrenton to DC Line (3-20-22 designation predates US 29)
Rawley White Martin Memorial Bridge over Bannister River (3-6-42); Nathaniel B. Early Bridge over Rapidan River (2-8-28 designation predates US 29)
Other names:  Wards Rd (Campbell Co); Richmond Hwy (Lynchburg); N. Amherst Hwy (Amherst Co n of US 29 Bus); Thomas Nelson Hwy (Nelson Co); Monacan Trail Rd (Albemarle Co s of US 250); Emmet St (Charlottesville); James Monroe Hwy (Culpeper Co s of US 15); James Madison Hwy (US 15 duplex south of Warrenton); Eastern Bypass (Warrenton); Washington St (Falls Church); Old Dominion Dr (Arlington Co)
Scenic Byway:  No segments
Comments: One of the three most important non-interstates in Virginia (with US 58 and US 460).
US 29 is posted as future I-785 corridor south of US 58-360. Thoughts of extending I-785 further north to Lynchburg exist and this wouldn't be all that difficult. Thoughts of continuing this to Charlottesville are crazy as this would be difficult terrain.
VDOT would like to 4-lane US 29 through the Manassas Battlefield to alleviate traffic woes but the National Park Service is against this. A plan has surfaced to route it and VA 234 around the north of the Battlefield.
In the 30's and 40's there was a VA 29 loop similar to the US 360-VA 360 setup between Culpeper and Warrenton.