Query pages based on tags

This is because you haven’t mentioned post_type here and by default post_type is 'post' and hence it is missing the pages,

add the below in your query

'post_type' => array( 'post', 'page' )

Like this 

$articles = new WP_Query( array(
    'showposts' => -1,
    'tag' => $tag,
    'meta_key' => 'date',
    'orderby' => 'meta_value_num',
    'order' => 'DESC',
    'post_type' => array( 'post', 'page' )
)

Related Posts:

  1. Proper way to get page content
  2. Get wp_get_attachment_url outside of loop
  3. WordPress parent select need to be removed
  4. How to create wordpress page that shows posts with specific tags?
  5. How to exclude shortcode from specific page IDs if it’s set to global
  6. How to get the excerpt of a page before more tag?
  7. How to echo excerpts with wp_list_pages?
  8. Page displays content from different query?
  9. How to make tag post listing page working?
  10. How to retrieve attachments from child pages of a specific Page?
  11. Custom page with queries returns 404
  12. Query specific Pages
  13. How to get tagged pages to show up with tagged posts?
  14. Show content if page is a grandchild of top level page
  15. Get all pages to display at once
  16. trying to add a author value in wp page links?
  17. Attach link to pages accoding to tags
  18. Search Page: activate html code if the tag is on the page
  19. Filter posts by author selected in page
  20. Tags are automatically converted if they match post names. Stop It!
  21. Display list of posts with x tag within a page?
  22. Add tags to long page that is broken up into subpages?
  23. How to get a list of pages (not posts) with specific tags?
  24. How to disable posts and use pages only
  25. Custom SQL Query for WordPress page
  26. Get next/previous cousin page
  27. I want only my sub-pages to be clickable in the navbar
  28. How restrict page for users logged? [closed]
  29. Only allow new subpages to be created
  30. Hide Visibility Option From WordPress Publish Metabox
  31. How do I turn comments off for pages, but not posts?
  32. How to make nested page structure?
  33. List Child Pages of Parent Parent Page (Child pages from Grand Parent)
  34. How to add meta boxes to Pages
  35. Form action redirect to the same page
  36. How do I create a separate page for each author?
  37. Overriding the currently selected menu item
  38. Missing parent page attribute
  39. Hiding Page by Title from Editing
  40. Two Search pages, One search form
  41. Get page by its ID and display it on another one
  42. creating and styling a within a page
  43. How do i change page template in bulk?
  44. What are trackbacks?
  45. How to enumerate a list of posts?
  46. How can I redirect to my custom page without loading the Dashboard itself?
  47. Remove ID page from wp_count
  48. category slug and page slug same
  49. New user Registration data imported into Page
  50. Could be a namespace conflict (?) with login form and register form on the same page
  51. The concept of non-blog content
  52. Updated WordPress, now getting errors on site
  53. Edit Parent page drop menu when creating a page
  54. Get parent of current page
  55. How to list a page tree?
  56. How to create a page and display only the posts with a specific custom field value?
  57. Attachment pages stealing page slugs
  58. How to add an external php page with wordpress?
  59. Exclude pages by menu order
  60. WordPress pages not working out correctly with HTML
  61. Change page name in admin list
  62. How to exclude authors from get_pages()
  63. Folder wordpress page redirect
  64. Dynamic page with comments
  65. How to rewrite a page url
  66. Manage content on multiple pages synchronysly?
  67. Display pages in alphabetical order
  68. Get rid of “comment” field on non-blog pages [duplicate]
  69. How to control display of page lists on sidebar that doesn’t have childrens
  70. Is there a template tag/function for getting the URL (or slug or name or ID) of the blog page when using a “static” front page
  71. Problems in creating a static site with WordPress
  72. Creating new page/tab in groups section not working! [closed]
  73. Add separate list of pages under Admin
  74. add title to widgets of wordpress
  75. Custom user tables not working after migration
  76. remove “Edit” from select pages
  77. Add custom action to the page listing screen
  78. How to list pages from an author?
  79. How can a .css file be applied to a virtual page?
  80. WordPress blog posts template bug [closed]
  81. Checkboxes to automatically create pages when I activate a theme
  82. Cannot update page – with too many characters?
  83. Is it possible to embedd this web app to my website [duplicate]
  84. Using external DB within wordpress
  85. Exclude Posts from a Widget
  86. My pages disappeared from the list
  87. Pre-populating new Page creation with shortcodes
  88. WordPress Pages “allow comments” meta option can’t be checked
  89. How to display time when page is created and edited
  90. Loading internal page
  91. Firing page_publish where page is child page
  92. Google indexed pages for one page site
  93. Parent for a single (single.php)
  94. Create a new page for each form selection
  95. How can one get page by pagename if it is a child page?
  96. Archive with specific keyword by category sorted by date
  97. How to pass the Querystring in pages?
  98. Is it possible to keep the page title from actually appearing at the top of the page?
  99. Edit the text location of a form
  100. Fresh WordPress installation not able to simply show page content