Context : The Galactic plane has been observed extensively by a large number of Galactic plane surveys from infrared to radio wavelengths at an angular resolution below 40″ .
However , a 21 cm line and continuum survey with comparable spatial resolution is lacking .

Aims : The first half of THOR data ( l = 14.0 \degr - 37.9 \degr , and l = 47.1 \degr - 51.2 \degr , \lvert b \rvert \leq 1.25 \degr ) has been published in our data release 1 paper .
With this data release 2 paper , we publish all the remaining spectral line data and Stokes I continuum data with high angular resolution ( 10″–40″ ) , including a new H i dataset for the whole THOR survey region ( l = 14.0 - 67.4 \degr and \lvert b \rvert \leq 1.25 \degr ) .
As we published the results of OH lines and continuum emission elsewhere , we concentrate on the H i analysis in this paper .

Methods : With the Karl G. Jansky Very Large Array ( VLA ) in C-configuration , we observed a large portion of the first Galactic quadrant , achieving an angular resolution of \leq 40 ″ .
At L Band , the WIDAR correlator at the VLA was set to cover the 21 cm H i line , four OH transitions , a series of H n \alpha radio recombination lines ( RRLs ; n = 151 to 186 ) , and eight 128 MHz-wide continuum spectral windows ( SPWs ) , simultaneously .

Results : We publish all OH and RRL data from the C-configuration observations , and a new H i dataset combining VLA C+D+GBT ( VLA D-configuration and GBT data are from the VLA Galactic Plane Survey ) for the whole survey .
The H i emission shows clear filamentary substructures at negative velocities with low velocity crowding .
The emission at positive velocities is more smeared-out , likely due to higher spatial and velocity crowding of structures at the positive velocities .
Compared to the spiral arm model of the Milky Way , the atomic gas follows the Sagittarius and Perseus Arm well , but with significant material in the inter-arm regions .
With the C-configuration-only H i +continuum data , we produced a H i optical depth map of the THOR areal coverage from 228 absorption spectra with the nearest-neighbor method .
With this \tau map , we corrected the H i emission for optical depth , and the derived column density is 38 % higher than the column density with optically thin assumption .
The total H i mass with optical depth correction in the survey region is 4.7 \times 10 ^ { 8 } ~ { } M _ { \odot } , 31 % more than the mass derived assuming the emission is optically thin .
If we applied this 31 % correction to the whole Milky Way , the total atomic gas mass would be 9.4–10.5 \times 10 ^ { 9 } ~ { } M _ { \odot } .
Comparing the H I with existing CO data , we find a significant increase in the atomic-to-molecular gas ratio from the spiral arms to the inter-arm regions .

Conclusions : The high-sensitivity and resolution THOR H i dataset provides an important new window on the physical and kinematic properties of gas in the inner Galaxy .
Although the optical depth we derive is a lower limit , our study shows that the optical depth correction is significant for H i column density and mass estimation .
Together with the OH , RRL and continuum emission from the THOR survey , these new H i data provide the basis for high-angular-resolution studies of the interstellar medium ( ISM ) in different phases .